95 results on '"Song, Xiaogang"'
Search Results
2. Study on Microstructure and Properties of CoMoCrNi Coating Prepared by Vacuum Cladding
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JIA Keming, HU Ming, YU Haicheng, JIAO Yufeng, LIU Jinlong, SONG Xiaogang
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vacuum cladding ,comocrni ,structure ,wear resistance ,corrosion resistance ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Technology - Abstract
For improving the wear resistance and corrosion resistance of 38CrMoAl steel substrate, CoMoCrNi alloy powder was used as the research object to be mixed with a special binder and coated on the surface of 38CrMoAl steel substrate,and subsequently,the CoMoCrNi coating was prepared by vacuum cladding.The structure and comprehensive performance of the coating were investigated through XRD, SEM and its accompanying EDS instrument, hardness test, abrasive wear test, acidic salt spray test and electrochemical corrosion test.Results showed that the as-prepared CoMoCrNi coating had the smooth surface with metallic luster.The coating was composed of Co-based solid solution and Co3Mo2Si hard Laves phase, and the structure was fine, uniform and dense.In addition, a strong metallurgical bond was formed between the CoMoCrNi coating and the substrate.The micro-Vickers hardness of the substrate/coating exhibited a gradient distribution pattern, and there were dispersed hard phases in the coating,which had a much higher microhardness than the substrate.The wear resistance and corrosion resistance of CoMoCrNi coating were higher than those of the base material.Furthermore, compared with the self-fluxing cobalt-based alloy coatings prepared by current mainstream surface processing technologies such as laser cladding and surfacing welding, the CoMoCrNi coating prepared by the vacuum cladding method showed better wear resistance and corrosion resistance.In general, the coating possessed a stronger comprehensive load-bearing capacity, which could be expected to be used in complex working conditions.
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- 2023
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3. TransBoNet: Learning camera localization with Transformer Bottleneck and Attention
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Song, Xiaogang, Li, Hongjuan, Liang, Li, Shi, Weiwei, Xie, Guo, Lu, Xiaofeng, and Hei, Xinhong
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- 2024
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4. Image super-resolution with multi-scale fractal residual attention network
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Song, Xiaogang, Liu, Wanbo, Liang, Li, Shi, Weiwei, Xie, Guo, Lu, Xiaofeng, and Hei, Xinhong
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- 2023
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5. Mesoscale modelling of the FRP-concrete debonding mechanism in the pull-off test
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Wang, Xuan, Zhao, Tianlin, Guo, Jialong, Zhang, Zihua, and Song, Xiaogang
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- 2023
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6. The Carbon Emissions from Public Buildings in China: A Systematic Analysis of Evolution and Spillover Effects.
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Song, Xiaogang, Zhai, Shufan, and Zhou, Na
- Abstract
Public buildings, being the primary source of carbon emissions in China's construction sector, present a pressing need for emission control. This imperative task not only ensures the sustainable progression of China's building industry but also holds pivotal significance in the realm of global energy conservation and emission curtailment. This study analyzed the spatiotemporal evolution of carbon emissions from public buildings in China and assessed the spatial influence of related factors using a dataset covering 30 provincial units from 2006 to 2021. The analysis employed Theil's index, Moran's I index, standard deviation ellipse, and the spatial Durbin model. The study revealed an upward trajectory in carbon emissions from public buildings in China, although the growth rate was generally decreasing. Disparities in emission distribution among provincial units stem largely from intra-regional distinctions, notably prominent in the Low-Intensity High-Economy regions. Provincial carbon emissions from public buildings exhibited significant spatial correlation, manifesting as clusters of high–high and low–low patterns, indicative of mutual influence among adjacent areas. Additionally, the shift in carbon emission focal points from the northeast to the southwest underscored a more pronounced surge in the southwestern regions. Variables such as energy intensity, energy structure, per capita public building area, disposable income per capita, openness level, and environmental governance directly impact carbon emissions from public buildings. Among these, energy intensity, energy structure, disposable income per capita, and environmental governance also had spatial spillover effects. These findings provide a scientific reference and a foundation for policy-making, aiding local administrations in crafting strategies to mitigate carbon emissions from public buildings and foster sustainable progress. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Similarity-based meta-learning network with adversarial domain adaptation for cross-domain fault identification
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Feng, Yong, Chen, Jinglong, Yang, Zhuozheng, Song, Xiaogang, Chang, Yuanhong, He, Shuilong, Xu, Enyong, and Zhou, Zitong
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- 2021
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8. Liftoff of a New Hovering Oscillating-wing Micro Aerial Vehicle
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Zhou, Xiangcong, Zhang, Deyuan, Huang, Zhiyong, Song, Xiaogang, Liu, Hao, and Feng, Lin
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- 2021
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9. Three-dimensional fault geometry and kinematics of the 2008 Mw 7.1 Yutian earthquake revealed by very-high resolution satellite stereo imagery
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Song, Xiaogang, Han, Nana, Shan, Xinjian, Wang, Chisheng, Zhang, Yingfeng, Yin, Hao, Zhang, Guohong, and Xiu, Wenqun
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- 2019
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10. Paleoseismic study on the Pingdingshan-Annanba segments of the Altyn Tagh Fault based on offset clusters
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Han, Nana, Shan, Xinjian, Song, Xiaogang, Ren, Zhikun, Gong, Wenyu, Wang, Zhenjie, and Zhang, Yingfeng
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- 2018
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11. Microstructure and tensile properties of high-entropy alloy Al0.5CoCrFeNi particles reinforced Ti/Al laminated composite.
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Wang, Enhao, Lv, Lisong, Kang, Fuwei, Li, Shangzhuo, Lin, Chunfa, Han, Yuqiang, Li, Jiaqi, Song, Xiaogang, and Jiang, Wei
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LAMINATED materials ,TITANIUM composites ,MATERIALS testing ,ALUMINUM composites ,MICROSTRUCTURE ,FRACTURE mechanics ,MATERIAL plasticity ,ALLOYS - Abstract
Novel Ti/Al laminated composite embedded with particles of the high entropy alloy Al
0.5 CoCrFeNi were produced by vacuum hot press sintering at 650°C. The microstructure of the laminated composite was investigated using XRD, SEM, EDS, TEM and EBSD techniques. It was found that a thin layer of Al3 Ti was formed at the Ti/Al interface. There were no obvious defects between the Al0.5 CoCrFeNi particles and Al matrix, achieving a good interfacial bond. The tensile properties of the material were tested at room temperature. The results of the tensile test indicated that the material exhibited an elongation to failure of 59% and an average tensile strength of 240 MPa, demonstrating excellent plastic deformation capability. During the tensile process, the expansion of fractures and cracks in Al0.5 CoCrFeNi particles can consume energy, which helps to improve the material's ability to undergo plastic deformation. Based on the morphologies of tensile fracture, it has been observed that the fracture surface of high entropy alloys exhibits a mixed fracture mode consisting of both brittle and plastic fracture. The brittle BCC phase has been identified as the main cause of cracking in HEA. Ultimately, the material fractures due to necking. [ABSTRACT FROM AUTHOR]- Published
- 2024
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12. Earthquake potential across the North–South seismic belt of China.
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Li, Yanchuan, Shan, Xinjian, Qu, Chunyan, Zhang, Guohong, and Song, Xiaogang
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- 2024
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13. An Accurate Dynamic Model Identification Method of an Industrial Robot Based on Double-Encoder Compensation.
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Liu, Xun, Xu, Yan, Song, Xiaogang, Wu, Tuochang, Zhang, Lin, and Zhao, Yanzheng
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INDUSTRIAL robots ,DYNAMIC models ,GAUSSIAN mixture models ,LEAST squares ,MANIPULATORS (Machinery) ,PARAMETER identification - Abstract
Aiming at the challenges to accurately simulate complex friction models, link dynamics, and part uncertainty for high-precision robot-based manufacturing considering mechanical deformation and resonance, this study proposes a high-precision dynamic identification method with a double encoder. Considering the influence of the dynamic model of the manipulator on its control accuracy, a three-iterative global parameter identification method based on the least square method and GMM (Gaussian Mixture Model) under the optimized excitation trajectory is proposed. Firstly, a bidirectional friction model is constructed to avoid using residual torque to reduce the identification accuracy. Secondly, the condition number of the block regression matrix is used as the optimization objective. Finally, the joint torque is theoretically identified with the weighted least squares method. A nonlinear model distinguishing between high and low speeds was established to fit the nonlinear friction of the robot. By converting the position and velocity of the motor-side encoder to the linkage side using the deceleration ratio, the deformation quantity could be calculated based on the discrepancy between theoretical and actual values. The GMM algorithm is used to compensate the uncertainty torque that was caused by model inaccuracy. The effectiveness of the proposed method is verified by a simulation and experiment on a 6-DoF industrial robot. Results prove that the proposed method can enhance the online torque estimation performance by up to 20%. [ABSTRACT FROM AUTHOR]
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- 2023
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14. A stochastic approach for the reliability evaluation of multi-state systems with dependent components
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Song, Xiaogang, Zhai, Zhengjun, Liu, Yidong, and Han, Jie
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- 2018
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15. A Hyper-redundant Elephant’s Trunk Robot with an Open Structure: Design, Kinematics, Control and Prototype
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Zhao, Yongjie, Song, Xiaogang, Zhang, Xingwei, and Lu, Xinjian
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- 2020
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16. Three-dimensional mesoscale modelling of concrete composites by using random walking algorithm
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Zhang, Zihua, Song, Xiaogang, Liu, Yan, Wu, Di, and Song, Chongmin
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- 2017
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17. Deriving 3D coseismic deformation field by combining GPS and InSAR data based on the elastic dislocation model
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Song, Xiaogang, Jiang, Yu, Shan, Xinjian, and Qu, Chunyan
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- 2017
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18. Present-Day Crustal Deformation of the Northwestern Tibetan Plateau Based on InSAR Measurements.
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Zhang, Guifang, Qu, Chunyan, Shan, Xinjian, Song, Xiaogang, Zhang, Yingfeng, and Li, Yanchuan
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SYNTHETIC aperture radar ,SCREW dislocations ,PLATEAUS - Abstract
In this study, The ENVISAT advanced synthetic aperture radar observations from 2003 to 2010 of a descending track covering an area of 100 km × 300 km were used to map the surface velocity field in northwestern Tibet. The derived line-of-sight (LOS) velocity map revealed that interseismic deformation was mainly located on the Altyn Tagh Fault (ATF) and other four immature subsidiary faults (i.e., Tashikule Fault, Muzitage-jingyuhe Fault, Heishibeihu Fault, and Woniuhu Fault). A 2D elastic screw dislocation model was used to interpret the interferometric synthetic aperture radar (InSAR) velocity profiles, which revealed the following results. (a) The oblique movement is partitioned between left-lateral slip at a rate of 6.3 ± 1.4 mm/y on the ATF and 5.9 ± 2.8 mm/y on the subsidiary faults. The low slip rate of the ATF indicates that the ATF does not drive the northeastward extrusion of material, with most of the extrusion occurring in the eastern interior of the plateau and the four subsidiary faults localizing the oblique convergence partitioned in the west. This can reasonably explain why catastrophic earthquakes and rapid slip do not occur all over along the ATF. (b) Based on the four subsidiary faults accommodating the oblique movement and the traces amalgamation with the EKLF (delineated Bayan Har plate boundary to the northeast), we concluded guardedly that the four subsidiary faults are the evoluting plate boundary of the Bayan Har block to the northwest. (c) The Tanan top-up structure had an uplift rate of ~0.6 mm/y at the south of the Tarim Basin. [ABSTRACT FROM AUTHOR]
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- 2023
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19. Effects of resveratrol on tolerance to ischemia/reperfusion injury in aged male mice: Role of autophagy and apoptosis.
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Song, Xiaogang, Wei, Chao, Huang, Hui, Cao, Xingdan, Chen, Ziyi, Chen, Yongqing, and Wu, Bing
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REPERFUSION injury , *RESVERATROL , *APOPTOSIS , *AUTOPHAGY , *ISCHEMIA , *MICE , *MYOCARDIAL reperfusion - Abstract
Aged myocardium is more susceptible to ischemia/reperfusion (I/R) injury. Autophagy and apoptosis play important roles in cardiac I/R injury. However, whether resveratrol can reduce the I/R vulnerability of aged myocardium by regulating apoptosis and autophagy remains unclear. The present study aimed to investigate the effect of resveratrol on the tolerance to I/R injury in aged male mice and to determine the contribution of apoptosis and autophagy. We used aged C57 mice as our research subjects. The hearts of mice were isolated after 6 weeks of intragastric administration with resveratrol and subsequently perfused with Krebs–Henseleit buffer to produce the I/R model. We found that resveratrol alleviated cardiac I/R injury in aged mice, but not in SIRT1+/− mice. Aged mice exhibited decreased LC3 and Beclin1 expressions, which were significantly rescued by resveratrol treatment. In addition, resveratrol decreased the expression of Bax and the activity of Caspase‐3, while increasing the expression of Bcl‐2 and the activity of SIRT1 in aged mouse hearts. Coimmunoprecipitation assays revealed that resveratrol facilitated the binding of Bax to Bcl‐2 and the dissociation of Bcl‐2 from Beclin1 in aged mouse myocardium. Conversely, SIRT1 knockout enhanced the formation of the Beclin1/Bcl‐2 complex and disrupted the interaction between Bcl‐2 and Bax. The above results indicate that resveratrol can reduce the vulnerability of myocardial I/R injury in senile myocardium by inhibiting apoptosis and upregulating autophagy through the SIRT1 signaling pathway. [ABSTRACT FROM AUTHOR]
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- 2023
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20. Enhanced Properties of Ti/Al Laminated Composite Reinforced by High-Entropy Alloy Particles.
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Wang, Enhao, Lv, Lisong, Kang, Fuwei, Li, Shangzhuo, Li, Jiaqi, Tian, Yao, Jiang, Wei, and Song, Xiaogang
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TITANIUM composites ,LAMINATED materials ,ELECTRON backscattering ,TRANSMISSION electron microscopes ,SCANNING electron microscopes ,INTERMETALLIC compounds ,ALLOYS - Abstract
Novel HEA
p -Ti/Al laminated composites embedded with particles of the high-entropy alloy Al0.5 CoCrFeNi (HEA) were fabricated by vacuum hot-press sintering at 730 °C. The phase composition and microstructure of the composites were studied with X-ray diffractometer (XRD), scanning electron microscope SEM, energy dispersive spectrometer (EDS), transmission electron microscope (TEM), and electron backscattering diffraction (EBSD) techniques. At this temperature, it has been observed that Al3 Ti intermetallic compound is the favored phase and the reaction results in the dispersion of Al3 Ti in the original Al layer. A large number of interfaces are formed between Al3 Ti and Al. The deformed Al3 Ti grains are concentrated in the interface near the Ti side. The mechanical properties, including tensile and compressive properties at room temperature, were analyzed. The tensile test results indicate that the composite exhibited an average tensile strength of 258 MPa and an average yield strain of 9.86%. Compression test results show that when a load perpendicular to the layer is applied, the yield strain and yield stress of the material are 9.67% and 474.09 MPa, respectively. Moreover, under a load parallel to the layer, the material fails due to interfacial debonding. [ABSTRACT FROM AUTHOR]- Published
- 2023
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21. InSAR-derived present-day crustal movement of Daliangshan on the southeastern margin of the Qinghai–Tibetan Plateau.
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Gong, Wenyu, Song, Xiaogang, Zhang, Yingfeng, Hua, Jun, Sun, Haoyue, Zhao, Dezheng, Zhu, Chuanhua, and Shan, Xianjian
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SYNTHETIC aperture radar , *GLOBAL Positioning System , *SYNTHETIC apertures , *STRAINS & stresses (Mechanics) , *RADAR interferometry , *ROTATIONAL motion , *MOTION - Abstract
The Daliangshan area of Sichuan, China, is located on the southeastern margin of the Qinghai–Tibetan Plateau. It marks the central section of the left‐lateral Xianshuihe–Xiaojiang Fault System (XXFS), which plays a crucial role in accommodating clockwise vertical-axis rotation of the expanding Qinghai–Tibetan Plateau relative to the South China Block. The area is seismically and tectonically active, and three major active faults—the Anninghe fault (ANHF), Zemuhe fault (ZMHF) and Daliangshan fault (DLSF)—together accommodate a significant amount of left-lateral strike-slip motion. Here, we present a geodetic study of the Daliangshan area mainly based on satellite interferometric synthetic aperture radar (InSAR). We processed Advanced Land Observing Satellite-2 (ALOS2) Phased-Array L-band Synthetic Aperture Radar-2 (PALSAR2) imagery to reconstruct the present-day interseismic deformation field. We developed an optimal atmospherics phase correction strategy to overcome the significant artefacts caused by ionospheric and tropospheric. By applying a multitemporal analysis on corrected interferograms, for the first time we generated a spatially continuous deformation rate field for the Daliangshan area. The satellite line-of-sight (LOS) rate field agrees with Global Positioning System (GPS) and levelling data to ∼2 mm yr–1, confirming that our processing approach is suitable for use in heavily vegetated areas. The InSAR rate map reveals displacements along the central and southern segments of the DLSF and ZMHF. By applying an inversion based on the Okada model, we quantitatively estimated the kinematic parameters of fault segments. Assuming a simple rectangular fault plane for each fault segment and constrained with the prior knowledge of the left-lateral slip, we determined that the ZMHF has a slip rate of 5.06 |$\pm 0.99{\rm{\ mm}}\,{\rm{yr}}^{-1}$| with a rake angle of ∼ |$38^\circ $| gently dipping to the SW. The southern section of the DLSF has a rake of |$- 48^\circ \,\,{\rm to}\,\, - 41^\circ $| with the total slip rate of |$4.93 \pm 0.4{\rm{\ mm}}\,{\rm{yr}}^{-1}$| , dipping towards to the NE at |$63.50^\circ \pm 2.31^\circ $|. The modelled 3-D rate field has been validated with GPS and levelling measurements. Additionally, the inversion model and strain field suggest that the middle section of the DLSF undergoes strong deformation. We considered the implications of three factors—oblique convergence, gravity-driven movement, and the ELIP beneath the Sichuan–Yunnan area—for complex 3-D velocities in the transitional Daliangshan area. [ABSTRACT FROM AUTHOR]
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- 2023
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22. Deformation of the Haiyuan-Liupanshan fault zone inferred from the denser GPS observations
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Li, Yanchuan, Qu, Chunyan, Shan, Xinjian, Song, Xiaogang, Zhang, Guohong, Gan, Weijun, Wen, Shaoyan, and Wang, Zhenjie
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- 2015
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23. EZH2: An Accomplice of Gastric Cancer.
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Yu, Wuhan, Liu, Ning, Song, Xiaogang, Chen, Lang, Wang, Mancai, Xiao, Guohui, Li, Tengfei, Wang, Zheyuan, and Zhang, Youcheng
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STOMACH tumors ,NUCLEAR proteins ,GENE expression ,DNA methylation ,EPIGENOMICS - Abstract
Simple Summary: Enhancer of zeste homolog 2 (EZH2) modifies the trimethylation of Lys-27 of histone 3, affecting downstream target genes' expression. It was reported that EZH2 is highly expressed in gastric cancer and may be a potential prognostic molecule and promising therapeutic target. We aim to present the value of EZH2 research in gastric cancer by focusing on the crucial events of EZH2 involvement in gastric cancer progression. Therefore, in this review, we present the two main functions of EZH2: histone methylation modification and DNA methylation by EZH2; the molecular mechanism of the action of EZH2 in regulating target genes; a detailed description of the mechanism of EZH2 in gastric cancer-related events. Finally, progress in the development of EZH2 inhibitors is summarized. This review article provides researchers studying the epigenetics of gastric cancer with research ideas to find new targets for studying gastric cancer pathogenesis. Gastric cancer is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Understanding the factors influencing the therapeutic effects in gastric cancer patients and the molecular mechanism behind gastric cancer is still facing challenges. In addition to genetic alterations and environmental factors, it has been demonstrated that epigenetic mechanisms can also induce the occurrence and progression of gastric cancer. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressor complex 2 (PRC2), which trimethylates histone 3 at Lys-27 and regulates the expression of downstream target genes through epigenetic mechanisms. It has been found that EZH2 is overexpressed in the stomach, which promotes the progression of gastric cancer through multiple pathways. In addition, targeted inhibition of EZH2 expression can effectively delay the progression of gastric cancer and improve its resistance to chemotherapeutic agents. Given the many effects of EZH2 in gastric cancer, there are no studies to comprehensively describe this mechanism. Therefore, in this review, we first introduce EZH2 and clarify the mechanisms of abnormal expression of EZH2 in cancer. Secondly, we summarize the role of EZH2 in gastric cancer, which includes the association of the EZH2 gene with genetic susceptibility to GC, the correlation of the EZH2 gene with gastric carcinogenesis and invasive metastasis, the resistance to chemotherapeutic drugs of gastric cancer mediated by EZH2 and the high expression of EZH2 leading to poor prognosis of gastric cancer patients. Finally, we also clarify some of the current statuses of drug development regarding targeted inhibition of EZH2/PRC2 activity. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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24. Source characteristics of the Yutian earthquake in 2008 from inversion of the co-seismic deformation field mapped by InSAR
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Shan, Xinjian, Zhang, Guohong, Wang, Chisheng, Qu, Chunyan, Song, Xiaogang, Zhang, Guifang, and Guo, Liming
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- 2011
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25. Modified Characteristics Gauge–Uzawa Finite Element Method for Time Dependent Conduction–Convection Problems
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Si, Zhiyong, Song, Xiaogang, and Huang, Pengzhan
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- 2014
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26. Coupled Force–Position Control for Dynamic Contact Force Tracking in Uncertain Environment.
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Song, Xiaogang, Li, Bing, Xu, Wenfu, and Li, Zhisen
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IMPEDANCE control ,ADAPTIVE control systems ,INDUSTRIAL robots ,ROBOT control systems - Abstract
Both the position and force control of robots are needed in industrial manufacturing, such as in assembly and grinding, etc. In this paper, we concentrate on two issues. One is the system oscillation in traditional hybrid force–position control (HFPC) during switching between force and position control because the diagonal elements in the selection matrix are either 0 or 1. Another issue is the poor force-tracking performance of conventional impedance control, which depends on accurate environmental models. To address these issues, a coupled force–position control (CFPC) method is presented in this paper by combining the proposed adaptive impedance control method with a modified HFPC method. The selection matrix S of HFPC is replaced with a weighted matrix S w . A weighted matrix regulator is designed to realize smooth switching between position and force control by adjusting the matrix weights in real time, and an adaptive impedance control algorithm is proposed to improve the force-tracking performance in complex environments. To verify the feasibility of the CFPC method proposed in this paper, simulations and physical experiments were conducted. The results show that the CFPC method has the advantages of a better force-tracking performance and a smoother switching between position and force control compared to the traditional HFPC method. A grinding experiment was conducted to further compare the performances of the HFPC and CFPC methods. The roughness values of the ground plates were 0.059 μm for the HFPC method and 0.031 μm for the proposed CFPC method, which demonstrates that the proposed CFPC method has a better performance. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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27. Post-earthquake assessment of building damage degree using LiDAR data and imagery
- Author
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Li, ManChun, Cheng, Liang, Gong, JianYa, Liu, YongXue, Chen, ZhenJie, Li, FeiXue, Chen, Gang, Chen, Dong, and Song, XiaoGang
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- 2008
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28. A fuzzy adaptive admittance controller for force tracking in an uncertain contact environment.
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Li, Zhisen, Huang, Hailin, Song, Xiaogang, Xu, Wenfu, and Li, Bing
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ELECTRIC controllers ,ELECTRIC admittance ,ADAPTIVE control systems ,FUZZY logic ,IMPEDANCE control - Abstract
Traditional constant admittance controller (CAC) in uncertain contact environment is highly dependent on environmental location and stiffness, which are always difficult to obtain in most applications. To address this problem, a fuzzy adaptive admittance controller (FAAC) based on fuzzy inference rules is proposed in this paper. Firstly, an adaptive admittance controller (AAC) that can compensate for the admittance parameters in real time based on force error information is proposed. Secondly, a fuzzy logic loop is introduced into the adaptive term of the AAC system to reduce the overshoot when force tracking, thus creating the FAAC. The detailed design method of FAAC is presented, and the stability conditions are analysed. Finally, simulations and experiments are conducted in several dynamic environments to demonstrate the force tracking performance of the proposed controller. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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29. Tectonic and Geometric Control on Fault Kinematics of the 2021 Mw7.3 Maduo (China) Earthquake Inferred From Interseismic, Coseismic, and Postseismic InSAR Observations.
- Author
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Zhao, Dezheng, Qu, Chunyan, Chen, Han, Shan, Xinjian, Song, Xiaogang, and Gong, Wenyu
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SURFACE fault ruptures ,EARTHQUAKES ,SHEAR strain ,STRAIN rate ,KINEMATICS ,GEODETIC observations ,PALEOSEISMOLOGY - Abstract
The 2021 Mw7.3 Maduo (Qinghai, China) earthquake ruptured ∼160 km along a poorly known secondary fault inside the Bayanhar block on the northern Tibetan plateau, which is generally parallel to the Kunlun fault. Here we integrate the interseismic (2015–2020) and coseismic geodetic observations to quantify the interseismic strain rate, fault geometry and coseismic slip distribution. Our results reveal that the seismogenic fault is featured by the low (<20 nanostrain/yr) and nearly undetectable interseismic strain rate. Three‐dimensional displacement fields and coseismic strain maps demonstrate the spatial variations of rupture kinematics due to the change of fault geometry. Our study reveals the steeply north‐dipping fault geometry of the seismogenic fault. The majority of coseismic slip occurred between 0 and 15 km with slight shallow slip deficit, which not penetrates through the inferred elastic upper crust (∼20–25 km). Our study highlights the tectonic and geometric control on fault kinematics of the Maduo earthquake. Plain Language Summary: The Bayanhar block on the north‐central Tibetan plateau experienced several major earthquakes with Mw > 6.5 on the boundary faults since the 1997 Mw7.6 Manyi earthquake, which is consistent with fast long‐term slip rates and large locking depth. However, the potential of generating large earthquakes on the faults inside the Bayanhar block is typically considered to be insignificant due to the estimated low fault slip rate (<5 mm/yr) and limited fault length. The 2021 Mw7.3 Maduo earthquake occurred on a poorly known subsidiary fault inside the Bayanhar block. Here, we use InSAR measurements prior to (2015–2020) and during the earthquake to investigate interseismic strain accumulation, to map coseismic deformation and to constrain the fault geometry as well as coseismic slip distribution of the Maduo earthquake. The three‐dimensional displacement fields and the relocated aftershocks support a slightly off vertical, dipping to the north, fault geometry. Our inversion results show that the coseismic slip is mainly distributed at a depth of 0–15 km. The kinematic analysis of the Maduo earthquake demonstrates that long‐term quantification of earthquake hazard of the subsidiary strike‐slip fault inside the Bayanhar block is challenging, because the interseismic strain rate is remarkably low and is largely undetectable by the geodetic observations. Key Points: Interseismic strain rate, coseismic three‐dimensional displacement field, finite strain and short‐term postseismic deformation of the Maduo earthquakeThe 2021 Maduo earthquake occurred on a subsidiary fault with a low (<20 nanostrain/yr) interseismic shear strain rateLong (∼160 km) rupture of the Maduo earthquake features shallow slip deficit with multi‐segment slip not penetrating through the upper crust [ABSTRACT FROM AUTHOR]
- Published
- 2021
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30. A PD Computed Torque Control Method with Online Self-gain Tuning for a 3U P S- P S Parallel Robot.
- Author
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Song, Xiaogang, Zhao, Yongjie, Chen, Chengwei, Zhang, Liang'an, and Lu, Xinjian
- Subjects
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PARALLEL robots , *TORQUE control , *ROBOT control systems , *NONLINEAR control theory , *VIRTUAL work , *GENETIC algorithms , *SELF-tuning controllers - Abstract
SUMMARY: In this paper, an online self-gain tuning method of a PD computed torque control (CTC) is used for a 3UPS-PS parallel robot. The CTC is applied to the 3UPS-PS parallel robot based on the robot dynamic model which is established via a virtual work principle. The control system of the robot comprises a nonlinear feed-forward loop and a PD control feedback loop. To implement real-time online self-gain tuning, an adjustment method based on the genetic algorithm (GA) is proposed. Compared with the traditional CTC, the simulation results indicate that the control algorithm proposed in this study can not only enhance the anti-interference ability of the system but also improve the trajectory tracking speed and the accuracy of the 3UPS-PS parallel robot. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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31. Mesoscale damage modelling of concrete by using image-based scaled boundary finite element method.
- Author
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Zhang, Zihua, Guo, Jialong, Zhang, Zhenwen, and Song, Xiaogang
- Subjects
BOUNDARY element methods ,FINITE element method ,DAMAGE models ,RANDOM walks ,CONCRETE ,FRACTIONS - Abstract
As a thin layer surrounding aggregates, the interfacial transition zone (ITZ) has a significant influence on the mechanical performance of concrete, a large number of small elements is required to discretize the ITZ and its vicinity owing to its small thickness. In this contribution, the mesostructure of concrete is explicitly built by a novel method named improved random walking algorithm (IRWA), with which the grading, content, shape of aggregates and the thickness of ITZs, can be conveniently controlled by users, and high volume fraction of aggregate and remarkable efficiency can be achieved. In the framework of the scaled boundary finite element method (SBFEM), the image-based quadtree decomposition is employed to automatically generate the multi-level mesh for the concrete composites, with no trouble in dealing with hanging nodes or the dramatically changing element size in the vicinity of the material interface. The nonlocal damage model in integral format is extended to simulate progressive damage of concrete at mesoscale with good mesh independence. Four benchmarks are modelled to demonstrate the performance of the proposed approach, and the effects of model parameters on the structural responses are also discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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32. Geodetic Observations of Shallow Creep on the Laohushan‐Haiyuan Fault, Northeastern Tibet.
- Author
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Li, Yanchuan, Nocquet, Jean‐Mathieu, Shan, Xinjian, and Song, Xiaogang
- Subjects
AFTERSLIP ,EARTHQUAKE aftershocks ,GEODETIC observations ,GLOBAL Positioning System ,SEISMIC waves - Abstract
We investigated the spatial distribution of aseismic creep on the Laohushan‐Haiyuan fault using Global Positioning System (GPS) data (1999–2017) and Interferometric Synthetic Aperture Radar (InSAR) data (2003–2010). Comparisons among GPS, InSAR line‐of‐sight (LOS) rates, and leveling show that neither leveling nor GPS vertical velocities can fit the vertical signal mapped into the LOS, implying either complicated vertical crustal deformation in northeastern Tibet and/or complex error structures in the InSAR data. Thus, we combined horizontal GPS with high‐pass filtered InSAR data to produce a continuous LOS rate map crossing the fault. Our geodetic data reveal three creep sections along the fault. Both the restored LOS data and decomposed ascending and descending InSAR data highlight the fact that vertical motion can cause an overestimation of creep rate; we obtained a refined creep rate of 2.5 ± 0.4 mm/a on the Laohushan fault. We further identified a 10 km‐long, ∼3–5 mm/a creep section (∼104.2°E−104.3°E) and a 43 km‐long, ∼1–3 mm/a creep section (∼105.3°E−105.7°E) on the western and eastern Haiyuan fault respectively. Both are located on fault sections that ruptured during the 1920 M∼8 earthquake, suggesting that the 1920 earthquake was able to cross pre‐existing creep sections or that the fault shows heterogeneous relocking after large earthquakes, with creep lasting decades on some parts of the rupture. Fault coupling shows a highly variable rate of slip deficit accumulation along strike, suggesting that coupling might significantly evolve during the period between two large earthquakes. Plain Language Summary: Ample observations document slip on a fault plane is seismic and/or aseismic; the former situation refers to a fault slips suddenly and produce earthquakes, the latter means a fault slips gradually without generating seismic energy. Studying the fault‐creep activity contributes to better understand the seismic behavior of crustal faults. We focus on the Haiyuan fault system, which is located on the northeastern margin of Tibet. Several large earthquakes occurred along the fault system in the past, including the 1920 M∼8.0 Haiyuan and the 1927 M ∼8–8.3 Gulang earthquakes. Using Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data, we identified three creep sections along the fault. Our results show vertical deformation that has mapped into the InSAR line‐of‐sight (LOS) could leads to overestimation of the creep rate. Besides, our findings imply either large earthquakes can rupture creep regions or they can generate long‐lasting afterslip/creep. Key Points: Of three creep segments on the Laohushan‐Haiyuan fault, two are located along fault sections that ruptured during the 1920 M∼8 earthquakeVertical motion leads to overestimation of the creep rate on the Laohushan fault; our refined creep rate is 2.5 ± 0.4 mm/aOur findings support that large earthquakes can rupture pre‐existing creep regions or that they can generate long‐lasting afterslip or creep [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
33. Multifault complex rupture and afterslip associated with the 2018 Mw 6.4 Hualien earthquake in northeastern Taiwan.
- Author
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Zhao, Dezheng, Qu, Chunyan, Shan, Xinjian, Bürgmann, Roland, Gong, Wenyu, Tung, Hsin, Zhang, Guohong, Song, Xiaogang, and Qiao, Xin
- Subjects
EARTHQUAKE aftershocks ,EARTHQUAKES ,SURFACE fault ruptures ,RADAR interferometry ,TIME series analysis ,TIME management - Abstract
We investigate the coseismic and post-seismic deformation due to the 6 February 2018 M
w 6.4 Hualien earthquake to gain improved insights into the fault geometries and complex regional tectonics in this structural transition zone. We generate coseismic deformation fields using ascending and descending Sentinel-1A/B InSAR data and GPS data. Analysis of the aftershocks and InSAR measurements reveal complex multifault rupture during this event. We compare two fault model joint inversions of SAR, GPS and teleseismic body waves data to illuminate the involved seismogenic faults, coseismic slip distributions and rupture processes. Our preferred fault model suggests that both well-known active faults, the dominantly left-lateral Milun and Lingding faults, and previously unrecognized oblique-reverse west-dipping and north-dipping detachment faults, ruptured during this event. The maximum slip of ∼1.6 m occurred on the Milun fault at a depth of ∼2–5 km. We compute post-seismic displacement time series using the persistent scatterer method. The post-seismic range-change fields reveal large surface displacements mainly in the near-field of the Milun fault. Kinematic inversions constrained by cumulative InSAR displacements along two tracks indicate that the afterslip occurred on the Milun and Lingding faults and the west-dipping fault just to the east. The maximum cumulative afterslip of 0.4–0.6 m occurred along the Milun fault within ∼7 months of the main shock. The main shock-induced static Coulomb stress changes may have played an important role in driving the afterslip adjacent to coseismic high-slip zones on the Milun, Lingding and west-dipping faults. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
34. Coseismic and postseismic displacements from the 1978 Mw 7.3 Tabas-e-Golshan earthquake in eastern Iran
- Author
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Zhou, Yu, Walker, Richard T., Hollingsworth, James, Talebian, Morteza, Song, Xiaogang, and Parsons, Barry
- Published
- 2016
- Full Text
- View/download PDF
35. Enterprise management innovation in the internet of things from the perspective of contingency.
- Author
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Chen, Weiling, Song, Xiaogang, Guarda, Teresa, Lopes, Isabel, and Rocha, Álvaro
- Subjects
- *
INTERNET of things , *INNOVATION management , *GENETIC algorithms , *TECHNOLOGY management , *INFORMATION technology , *BUSINESS enterprises - Abstract
With the development of Internet and information technology, enterprises are facing more challenges. It is urgent and necessary to innovate the mode of enterprise management. In this paper, from the perspective of contingency, a multi-objective genetic algorithm is constructed to introduce Internet of Things technology into enterprise management innovation. Through the function to solve the relationship between the various operating entities of the enterprise, the algorithm obtains the optimal solution of vehicle distribution. Firstly, contingency theory is introduced into the innovative design of enterprise information system to optimize the logistics distribution path under the environment of the Internet of Things (IoT). The multi-objective genetic algorithm steps are designed, and the non-dominant set is constructed. The crossover and mutation operations of the objectives are combined to get the genetic sub-classes, and then the relationships among the parties in the enterprise logistics innovation management activities are solved. The experimental results show that the shortest running time of the algorithm is 0.56 seconds and the longest running time is 2.48 seconds. The average running time in the whole process is not more than 1 second, which meets the actual needs. The genetic algorithm can help enterprises to arrange the distribution path of logistics fleet reasonably. The research in this paper has enlightening effect on the management innovation of enterprises under the information environment, and further expands the application field of the IoT, which has practical significance. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
36. Geodetic Observations of the 2018 Mw 7.5 Sulawesi Earthquake and Its Implications for the Kinematics of the Palu Fault.
- Author
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Song, Xiaogang, Zhang, Yingfeng, Shan, Xinjian, Liu, Yunhua, Gong, Wenyu, and Qu, Chunyan
- Subjects
- *
EARTHQUAKES , *KINEMATICS , *FAULT zones , *STRUCTURAL geology , *SEISMOLOGY - Abstract
The ascending and descending interferometric synthetic aperture radar data are used to investigate the fault rupture and slip model of the 2018 Mw 7.5 Sulawesi, Indonesia, earthquake. The best fitting slip model indicates that this earthquake ruptured not only a segment extending the Palu fault to the north but also a northwestern segment offshore. The slip on the onshore fault is predominant left‐lateral strike slip. The slip on the offshore fault is dominated by normal faulting with a maximum slip of ~6.3 m. The newly discovered offshore normal faulting is likely to be the cause of the tsunami after the shock. Combined with previous geomorphic, tectonic, geodetic, and modeling studies, we suggest that the kinematics of the Palu fault maintained the same style of faulting from north to south, which resulted from an oblique extension occurred on an east dipping fault at depths. The deformation pattern of NW Sulawesi is dominated by this slip mechanism. Plain Language Summary: On 28 September 2018, a large earthquake (Mw 7.5) struck the Palu city, Sulawesi Island, eastern Indonesia, where three tectonic plates, the Indo‐Australian, Philippine Sea and Sunda Plates, interact. Using a joint analysis of ALOS‐2 and Landsat 8 satellite images, we found coseismic slip partitioning during this earthquake. We propose a conceptual structural model to interpret the slip mechanism, where oblique extension occurred on an east dipping fault at depth and the slip is partitioned into left‐lateral strike‐slip motion at the ground surface and normal faulting at the seabed surface. A similar small‐scale geological system is observed in the Palu basin along the same fault system, which provides good evidence for this mechanism. Our study has important implications for understanding the geohazards and deformation mechanism of faults in eastern Indonesia. Key Points: This earthquake ruptured one onshore segment with predominant strike‐slip motion and an offshore fault with a significant normal slipOffshore normal faulting is responsible for the tsunami after the earthquakeThis event revealed the kinematics of the Palu fault, which can be used to interpret the geomorphological expression in the Palu basin [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
37. Relationships between InSAR Seismic Deformation and Fault Motion Sense, Fault Strike, and Ascending/Descending Modes.
- Author
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QU, Chunyan, SHAN, Xinjian, ZHAO, Dezheng, ZHANG, Guohong, and SONG, Xiaogang
- Subjects
SYNTHETIC aperture radar ,GEOLOGIC faults ,DEFORMATIONS (Mechanics) ,DISPLACEMENT (Mechanics) ,COHERENT radar - Abstract
Based on the working principle of satellite radars, the earthquake deformation field measured by interferometric synthetic aperture (InSAR) is the projection of ground displacement associated with the seismogenic fault in the line of sight (LOS) of the satellite. However, LOS projections are complex, and are not only related to the ascending/descending modes and incidence angles of SAR data, but also related to the strike and motion senses of the fault. Even for the same earthquake, the LOS deformation derived from different ascending/descending data can be almost identical in one case, but quite different in another case, which makes the interpretation of InSAR seismic deformation and its comparison with field observations difficult. In this study, we undertook a quantitative analysis of the relationships between LOS observation sensitivity of InSAR and fault strike, fault motion sense, and ascending/descending modes, as well as 3D deformation fields. We studied the features and differences of the LOS deformation fields in different types of earthquakes using ascending/descending modes, with a particularly detailed analysis of the relations for a strike-slip type of earthquake. We also summarized the characteristics of LOS deformation fields of faults with different strikes and optimal observational data modes. Taking the strike-slip Yushu earthquake and the normal Gaize event as examples, we used SAR data of the ascending/descending modes to verify the results of quantitative calculations. These analyses will not only provide a more reasonable interpretation of InSAR seismic deformation fields and but also help understand the differences of seismic deformation fields revealed by data with different observational modes, therefore promoting the application of InSAR technology in seismology. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
38. COSEISMIC DEFORMATION FIELD AND FAULT SLIP DISTRIBUTION OF THE 2015 CHILE Mw8.3 EARTHQUAKE.
- Author
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Qu Chunyan, Zuo Ronghu, Shan XinJian, Zhang Guohong, Zhang Yingfeng, and Song Xiaogang
- Subjects
EARTHQUAKES ,DEFORMATION of surfaces ,GEOLOGIC faults - Abstract
On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m(Mw8.27), the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation. It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
39. Locking degree and slip rate deficit distribution on MHT fault before 2015 Nepal Mw 7.9 earthquake.
- Author
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Li, Yanchuan, Song, Xiaogang, Shan, Xinjian, Qu, Chunyan, and Wang, Zhenjie
- Subjects
- *
GEOLOGIC faults , *GLOBAL Positioning System , *NEPAL Earthquake, 2015 , *EARTHQUAKE hazard analysis , *PARAMETER estimation - Abstract
The spatial pattern and rate of strain accumulation on a fault during the pre- and inter-seismic phases are very important for interpreting the mechanism of earthquakes and evaluating seismic potentials. Here we use global positioning system (GPS) data and the block-dislocation model to invert for the locking degree and slip rate deficit of the Main Himalayan Thrust (MHT) fault in the southern margin of Tibet before the 2015 M w 7.9 Nepal earthquake. Results show that the locking depth and slip rate deficit increase from the west to the east. Along the western segment of the MHT fault (80°E–84°E), the locking depth is estimated to be 12–17 km with a slip rate deficit of 0–5 mm/a; along the central Nepal segment (84°E–87°E), the locking depth is 16–21 km with a slip rate deficit of 6–10 mm/a, whilst along the eastern segment (87°E–90°E), the locking depth increases to 23–26 km with a slip rate deficit of 8–13 mm/a. The 2015 Nepal earthquake initiated at the boundary between the western and central segments, an area with as where the slip rate deficit varies dramatically from 0 to 9 mm/a within 50 km resulting in high energy gradients. High strain concentration along the central and eastern segments leads to unilateral propagation of the rupture to the east. Given the paucity of large seismic events over the previous decades and the current high slip rate deficit, seismic hazard on the eastern Nepal segment remains high. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
40. China's part in Winter Olympics
- Author
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Song Xiaogang
- Subjects
China -- Social aspects ,Athletes -- Achievements and awards ,Business - Abstract
The 17th Winter Olympics at Lillehammer, Norway, witnessed the success of Chinese athletes who won a silver medal in the women's 500-meter speed skating event and a bronze in the 1000-meter speed skating. A few disappointing results were probably due to biased refereeing. China has to further accelerate its efforts to catch up with world standards in the Winter Olympics.
- Published
- 1994
41. Application of SNCR flue gas denitration technology in 330 MW CFB boiler.
- Author
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HAN Ying, GAO Hongpei, WANG Haitao, LI Li, WANG Runxi, and SONG Xiaogang
- Subjects
COMBUSTION research ,AMMONIA ,BOILERS ,UREA ,NITRIC oxide - Abstract
Owing to SNCR flue gas denitration technology and combustion control technology for CFB boiler, the NO
x concentration discharged by 1180 t/h CFB boiler decrease from 300 mg/m³ to less than 50 mg/m³. The denitration efficiency is above 80 percent, the ratio of ammonia to nitrogen is less than 1.5, ammonia escape value can be controlled under 1.5 mg/m³, automatic feeding rate is 100 percent. By optimizing operating parameters of SNCR system, get the optimum urea feeding concentration and ratio of ammonia to nitrogen, which guarantee the economy and stability of denitration system. This technology is first used in 330 MW CFB boiler, its operating experience provide reference for reducing NOx concentration discharged by CFB boiler. [ABSTRACT FROM AUTHOR]- Published
- 2013
42. Slip distribution of the 2008 Wenchuan M.
- Author
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Zhang, Guohong, Qu, Chunyan, Shan, Xinjian, Song, Xiaogang, Zhang, Guifang, Wang, Chisheng, Hu, Jyr-Ching, and Wang, Rongjiang
- Subjects
WENCHUAN Earthquake, China, 2008 ,INVERSIONS (Geology) ,GLOBAL Positioning System ,SYNTHETIC aperture radar ,ROCK deformation ,INTERFEROMETRY ,KINEMATICS ,GEODESY ,CRUST of the earth ,EARTH'S mantle ,EARTH (Planet) - Abstract
We investigate the slip distribution of the 2008 May 12 Wenchuan M 7.9 earthquake using GPS data and InSAR measurements under a linear inversion scheme, with emphasis on the effect of three factors, including constraint on rake, different discretizations, and layered elastic model. Within our inversion parameterization context, we find the most influential factor would be constraint on rake. Without constraint on rake, the slip model seems physically wrong under the depth of 15 km, due to the limited depth resolution of the geodetic data used, especially the one orbit of InSAR measurements. Thus it is necessary to add a priori to the slip rake to obtain a reasonable fault source model. Different discretizations of the subfault patches have a notable impact on the slip distribution. Also, the layered elastic model predicts more slip at depth than does the half-space model, by about 15-20 per cent. The characteristics of slip distribution established through our inversions include some points as follows: (1) the most reliable results would be expected at depth range of 0-15 km; (2) three peak-slip asperities are inverted, at Yingxiu county (near epicentre), Yuejiashan county, and Beichuan county, respectively; (3) the inverted rake along the Yingxiu-Beichuan fault changes from dominantly thrusting motion at the southwest segments to dominant right-lateral or even pure right-lateral strike slip at the northeast segments, and (4) only thrust slip is occurred on the Guanxian-Jiangyou fault. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
43. Application of High‐Resolution Remote Sensing Technology in Quantitative Study on Coseismic Surface Rupture Zones: An Example of the 2008 Mw7.2 Yutian Earthquake.
- Author
-
SHAN, Xinjian, SONG, Xiaogang, GONG, Wenyu, QU, Chunyan, ZHANG, Yingfeng, and HAN, Nana
- Subjects
- *
SURFACE fault ruptures , *EARTHQUAKES , *SEISMIC surveys , *REMOTE-sensing images , *QUANTITATIVE research , *DIGITAL elevation models - Abstract
The article discusses the research on surface rupture zone of seismic faults in China using high-resolution remote sensing technology and mentions the quantitative research of earthquakes. Topics include the survey on geometric and kinematic characteristics of the rupture zone; the 7.2 earthquake at Yutian in Xinjiang, China; and the use of digital elevation model the surface rupture behavior.
- Published
- 2018
- Full Text
- View/download PDF
44. Geometric Variation in the Surface Rupture of the 2018 Mw7.5 Palu Earthquake from Subpixel Optical Image Correlation.
- Author
-
Li, Chenglong, Zhang, Guohong, Shan, Xinjian, Zhao, Dezheng, and Song, Xiaogang
- Subjects
OPTICAL images ,GEOMETRIC surfaces ,SHEAR strain ,EARTHQUAKES ,SURFACE fault ruptures ,DEFORMATION of surfaces - Abstract
We obtained high-resolution (10 m) horizontal displacement fields from pre- and post-seismic Sentinel-2 optical images of the 2018 Mw7.5 Palu earthquake using subpixel image correlation. From these, we calculated the curl, divergence, and shear strain fields from the north-south (NS) and east-west (EW) displacement fields. Our results show that the surface rupture produced by the event was distributed within the Sulawesi neck (0.0974–0.6632°S) and Palu basin (0.8835–1.4206°S), and had a variable strike of 313.0–355.2° and strike slip of 2.00–6.62 m. The NS and EW displacement fields within the Palu basin included fine-scale displacements in both the near- and far-fault, the deformation patterns included a small restraining bend (localized shortening), a distributed rupture zone, and a major releasing bend (net extension) from the curl, divergence, and shear strain. Surface rupture was dominated by left-lateral strike-slip from initiation to termination, with a localized normal slip component peaking at ~3.75 m. The characteristics and geometric variation of the ruptured fault controlled both the formation of these surface deformation patterns and sustained supershear rupture. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
45. A Fine Velocity and Strain Rate Field of Present-Day Crustal Motion of the Northeastern Tibetan Plateau Inverted Jointly by InSAR and GPS.
- Author
-
Song, Xiaogang, Jiang, Yu, Shan, Xinjian, Gong, Wenyu, and Qu, Chunyan
- Subjects
- *
SYNTHETIC aperture radar , *STRUCTURAL geology , *GLOBAL Positioning System , *EARTHQUAKES , *FAULT diagnosis - Abstract
Interferometric synthetic aperture radar (InSAR) data from 6 Envisat ASAR descending tracks; spanning the 2003–2010 period; was used to measure interseismic strain accumulation across the Northeastern Tibetan Plateau. Mean line-of-sight (LOS) ratemaps are computed by stacking atmospheric-corrected and orbital-corrected interferograms. The ratemaps from one track with different atmospheric-corrected results or two parallel; partially overlapping tracks; show a consistent pattern of left-lateral motion across the fault; which demonstrates the MERIS and ECMWF atmospheric correction works satisfactorily for small stain measurement of this region; even with a limited number of interferograms. By combining the measurements of InSAR and GPS; a fine crustal deformation velocity and strain rate field was estimated on discrete points with irregular density depending on the fault location; which revealed that the present-day slip rate on the Haiyuan fault system varies little from west to east. A change (2–3 mm/year) in line-of-sight (LOS) deformation rate across the fault is observed from the Jinqianghe segment to its eastern end. Inversion from the cross-fault InSAR profiles gave a shallow locking depth of 3–6 km on the main rupture of the 1920 earthquake. We therefore infer that the middle-lower part of the seismogenic layer on the 1920 rupture is not yet fully locked since the 1920 large earthquake. Benefit from high spatial resolution InSAR data; a low strain accumulation zone with high strain rates on its two ends was detected; which corresponds to the creeping segment; i.e., the Laohushan fault segment. Contrary to the previous knowledge of squeezing structure; an abnormal tension zone is disclosed from the direction map of principal stress; which is consistent with the recent geological study. The distribution of principal stress also showed that the expanding frontier of the northeastern plateau has crossed the Liupan Shan fault zone; even arrived at the northeast area of the Xiaoguan Shan. This result agrees with the deep seismic reflection profile. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
46. GPS-Derived Fault Coupling of the Longmenshan Fault Associated with the 2008 Mw Wenchuan 7.9 Earthquake and Its Tectonic Implications.
- Author
-
Li, Yanchuan, Zhang, Guohong, Shan, Xinjian, Liu, Yunhua, Wu, Yanqiang, Liang, Hongbao, Qu, Chunyan, and Song, Xiaogang
- Subjects
GEOLOGIC faults ,GLOBAL Positioning System ,EARTHQUAKES ,PLATE tectonics ,WENCHUAN Earthquake, China, 2008 - Abstract
Investigating relationships between temporally- and spatially-related continental earthquakes is important for a better understanding of the crustal deformation, the mechanism of earthquake nucleation and occurrence, and the triggering effect between earthquakes. Here we utilize Global Positioning System (GPS) velocities before and after the 2008 Mw 7.9 Wenchuan earthquake to invert the fault coupling of the Longmenshan Fault (LMSF) and investigate the impact of the 2008 Mw 7.9 Wenchuan earthquake on the 2013 Mw 6.6 Lushan earthquake. The results indicate that, before the 2008 Mw 7.9 Wenchuan earthquake, fault segments were strongly coupled and locked at a depth of ~18 km along the central and northern LMSF. The seismic gap between the two earthquake rupture zones was only locked at a depth < 5 km. The southern LMSF was coupled at a depth of ~10 km. However, regions around the hypocenter of the 2013 Mw 6.6 Lushan earthquake were not coupled, with an average coupling coefficient ~0.3. After the 2008 Mw 7.9 Wenchuan earthquake, the central and northern LMSF, including part of the seismic gap, were decoupled, with an average coupling coefficient smaller than 0.2. The southern LMSF, however, was coupled to ~20 km depth. Regions around the hypocenter of the 2013 Mw 6.6 Lushan earthquake were also coupled. Moreover, by interpreting changes of the GPS velocities before and after the 2008 Mw 7.9 Wenchuan earthquake, we find that the upper crust of the eastern Tibet (i.e., the Bayan Har block), which was driven by the postseismic relaxation of the 2008 Mw 7.9 Wenchuan earthquake, thrust at an accelerating pace to the Sichuan block and result in enhanced compression and shear stress on the LMSF. Consequently, downdip coupling of the fault, together with the rapid accumulation of the elastic strain, lead to the occurrence of the 2013 Mw 6.6 Lushan earthquake. Finally, the quantity analysis on the seismic moment accumulated and released along the southern LMSF show that the 2013 Mw 6.6 Lushan earthquake should be defined as a “delayed” aftershock of the 2008 Mw 7.9 Wenchuan earthquake. The seismic risk is low along the seismic gap, but high on the unruptured southwesternmost area of the 2013 Mw 6.6 Lushan earthquake. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
47. Foraging Activities of Coptotermes formosanus in Subtropical Areas in China
- Author
-
Ruan, Guanhua, Song, Xiaogang, Hu, Yin, Han, Na, and Zhang, Dayu
- Published
- 2015
- Full Text
- View/download PDF
48. New insights into the 2010 Yushu Mw6.9 mainshock and Mw5.8 aftershock, China, from InSAR observations and inversion.
- Author
-
Zhao, Dezheng, Qu, Chunyan, Shan, Xinjian, Gong, Wenyu, Zhang, Guohong, and Song, Xiaogang
- Subjects
- *
EARTHQUAKE aftershocks , *SYNTHETIC aperture radar - Abstract
Abstract The Mw6.9 Yushu earthquake occurred on 14 April 2010, in Qinghai, China; the largest aftershock, a Mw5.8 event, occurred west of the mainshock on 29 May 2010 (˜40 days later). The aftershock had a different focal mechanism from the mainshock. Furthermore, seismicity after 29 May showed different spatial characteristics in terms of focal depth and distribution direction. To better understand the faulting and the relationship between these two events, we derived the whole displacement field caused by the Yushu mainshock and the Mw5.8 aftershock based on multi-perspective Interferometric Synthetic Aperture Radar (InSAR) data. We then conducted a robust inversion of the slip distribution jointly constrained by InSAR and GPS data. The results indicate that the Mw5.8 aftershock produced a separated deformation field with significant displacement changes of up to ˜4–6 cm, which indicates another intersecting ruptured fault at the west end of the Yushu fault. The slip distribution shows a 75-km NW rupture with a maximum slip of ˜2.1 m at a depth of ˜0–10 km on the main Yushu fault, and a 20 km NE rupture with peak slip of ˜0.4 m at a depth of ˜5–15 km on a vertical hidden fault. Both events showed a dominant left-lateral component. The total rupture length associated with the 2010 Yushu earthquake sequence reached ˜95 km. By calculating Coulomb stress changes, we confirmed that the mainshock triggered the Mw5.8 aftershock. Our results imply that the increased stress at the western end of the Yushu fault caused by the mainshock rupture may have played an important role in transferring the rupture plane from the Yushu fault to the NE hidden fault. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
49. Elastic block and strain modeling of GPS data around the Haiyuan-Liupanshan fault, northeastern Tibetan Plateau.
- Author
-
Li, Yanchuan, Shan, Xinjian, Qu, Chunyan, Zhang, Yingfeng, Song, Xiaogang, Jiang, Yu, Zhang, Guohong, Nocquet, Jean-Mathieu, Gong, Wenyu, Gan, Weijun, and Wang, Chisheng
- Subjects
- *
ELASTICITY , *GLOBAL Positioning System , *SOIL mechanics , *GEOLOGIC faults , *STRAINS & stresses (Mechanics) - Abstract
Based on the dense GPS velocity field in the northeastern margin of the Tibetan Plateau from 1999 to 2016, we have produced the deformation and strain characteristics of the Haiyuan fault and the Liupanshan fault. Estimated long-term slip rate along the Haiyuan-Liupanshan fault zones show a gradual decrease from 6.4 ± 1.6 mm/yr at the Tuolaishan fault to 2.9 ± 1.2 mm/yr at the Southern Liupanshan fault. Left-lateral thrusting movement was inverted for the Xiangshan-Tianjingshan fault (XS-TJS), which has an average slip rate of 2.1 ± 3.4 mm/yr during the study period. We also calculated the heterogeneous distribution of interseismic coupling along the fault zones. Our result also shows the locking depth of the Tianzhu seismic gap is ∼22 km. The slip rate deficit, the seismic moment accumulation rate, and the Coulomb stress accumulation rate are high on the fault planes, whereas the second invariant of the strain rate is low at the surface. The Liupanshan fault is locked to a depth of ∼23 km, and the corresponding seismic moment accumulation rate on the fault plane is high, while the strain rate at the surface is low. The accumulated strain along the Tianzhu seismic gap and the Liupanshan fault could be balanced by earthquakes with magnitudes of Mw7.9 and Mw7.4, considering the absence of large earthquakes over the last 1000 years and 1400 years respectively. The Haiyuan segments had ruptured during 1920 Haiyuan earthquake, and the estimated locking depth for period 1999–2016 is 5–10 km. Its seismic moment accumulation rate at depth is low and the strain rate at the surface is high. Our result indicates that 70% of the strike-slip along the Haiyuan segments transforms into thrusting along the Liupanshan fault, while the remaining 30% is related to the orogeny of the Liupanshan. For slip between the Haiyuan fault and the XS-TJS, about 27–34% of the slip is partitioned on the XS-TJS. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
50. Coseismic deformation fields and a fault slip model for the Mw7.8 mainshock and Mw7.3 aftershock of the Gorkha-Nepal 2015 earthquake derived from Sentinel-1A SAR interferometry.
- Author
-
Zuo, Ronghu, Qu, Chunyan, Shan, XinJian, Zhang, Guohong, and Song, Xiaogang
- Subjects
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DEFORMATIONS (Mechanics) , *SEISMIC surveys , *NEPAL Earthquake, 2015 , *INTERFEROMETRY , *GRAVITATIONAL potential , *DATA analysis - Abstract
Coseismic deformation fields caused by the moment magnitude (Mw)7.8 mainshock and Mw7.3 aftershock of the 2015 Gorkha-Nepal earthquake are obtained by analyzing Sentinel-1A/IW ascending and descending interferometry data. Results show that the deformation field associated with the Mw7.8 mainshock roughly resembles a prolate ellipse, extending from the epicenter about 20° east by south. The main region of deformation is about 160 km by 110 km, comprising a large southern area of uplift, and a small northern area of subsidence. Assuming that rupture occurred in a homogeneous elastic half-space, the coseismic fault slip models of the mainshock and aftershock are inverted based on a shallow dip fault constrained by the three data sets, Sentinel-1A/IW descending data, ascending data, and ALOS-2 descending data, separately or in combination. Mainshock slip distributions generated from all three data sets are similar, and inversion constrained by all three in combination reveal a comprehensive fault slip model. Indeed, coseismic slip is mainly distributed within a narrow 40 km zone to the north of the Main Frontal Trust (MFT), and at 6–15 km subsurface depth. In addition, the maximum slip in this event was about 5.1 m, the Mw7.8 mainshock ruptured the deep part of the seismogenic zone, while the region between the southern boundary of the rupture area and the MFT remained locked. Therefore, a considerable earthquake risk remains to the south of Kathmandu. The inverted coseismic slip of the Mw7.3 aftershock was concentrated in a small area, close to, and southeast of the epicenter, with maximum displacement of about 3 m. Finally, because there is no overlap between the two slip areas of the mainshock and aftershock, the gap between them, about 15 km in length, has additional potential to generate future earthquakes. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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