Investigation on Galloping of D-Shape Iced 6-Bundle Conductors in Transmission Tower Line

Mengqi Cai,Xiaohui Yang,Hanjie Huang,Linshu Zhou 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.6

The first comprehensive test base of electrical test transmission line in China has been established. Galloping response characteristics of real test tower-line system covered with D-shape ice model under natural wind load has been recorded. According to the structural details of the test tower-line, the detailed numerical model of the three spans tower-line system has been set up by nonlinear finite element method (FEM). Then, the digital stochastic wind field is presented. Galloping behaviors of the D-shape iced 6-bundle conductors in the test line under stochastic wind field is numerically simulated. Finally, the dynamic response of displacements, galloping traces, galloping modes, and frequencies are obtained. The numerical simulation results are consistent with the measured galloping characteristics results of the test transmission tower-line, which verifies the efficiency of the numerical model. It is demonstrated that the established FEM numerical method can be applied to investigate galloping behaviors of tower-line. Meanwhile, based on the numerical simulation results, the variation of stress and displacement of tower during galloping is also discussed.

Aerodynamic Characteristics of Iced 8-bundle Conductors under Different Turbulence Intensities

Mengqi Cai,Qian Xu,Linshu Zhou,Xiaohui Liu,Hanjie Huang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11

Iced conductor motion is induced by the aerodynamic instability. The aerodynamic characteristics of iced bundle conductors in turbulent flow are significantly different from that in uniform flow. The aerodynamic coefficients of iced 8-bundle conductors’ segment models under different turbulence intensities flow are measured by the wind tunnel experiment. Furthermore, the aerodynamic coefficients of each crescent- and sector-shape iced 8-bundle conductors under different turbulence intensities flow and ice thicknesses are obtained. The wind tunnel test results indicate there have obvious difference between aerodynamic characteristics of bundle conductors in turbulent flow and that in uniform flow. Then, key parameters, such as turbulence intensity, ice thickness and ice shape have significant influences on aerodynamic coefficients of each sub-conductors. Differences exist among aerodynamic coefficients of crescent-shape and sector-shape iced 8-bundle conductors. Finally, the galloping coefficients of iced 8-bundle conductors are discussed. The wind tunnel experiment results can offer useful reference resources for the comprehensive analysis of galloping of iced bundle conductors and their prevention techniques.

Ginsenoside compound K protects against cerebral ischemia/ reperfusion injury via Mul1/Mfn2-mediated mitochondrial dynamics and bioenergy

Qingxia Huang,Jing Li,Jinjin Chen,Zepeng Zhang,Peng Xu,Hongyu Qi,Zhaoqiang Chen,Jiaqi Liu,Jing Lu,Mengqi Shi,Yibin Zhang,Ying Ma,Daqing Zhao,Xiangyan Li The Korean Society of Ginseng 2023 Journal of Ginseng Research Vol.47 No.3

Background: Ginsenoside compound K (CK), the main active metabolite in Panax ginseng, has shown good safety and bioavailability in clinical trials and exerts neuroprotective effects in cerebral ischemic stroke. However, its potential role in the prevention of cerebral ischemia/reperfusion (I/R) injury remains unclear. Our study aimed to investigate the molecular mechanism of ginsenoside CK against cerebral I/R injury. Methods: We used a combination of in vitro and in vivo models, including oxygen and glucose deprivation/reperfusion induced PC12 cell model and middle cerebral artery occlusion/reperfusion induced rat model, to mimic I/R injury. Intracellular oxygen consumption and extracellular acidification rate were analyzed by Seahorse multifunctional energy metabolism system; ATP production was detected by luciferase method. The number and size of mitochondria were analyzed by transmission electron microscopy and MitoTracker probe combined with confocal laser microscopy. The potential mechanisms of ginsenoside CK on mitochondrial dynamics and bioenergy were evaluated by RNA interference, pharmacological antagonism combined with co-immunoprecipitation analysis and phenotypic analysis. Results: Ginsenoside CK pretreatment could attenuate mitochondrial translocation of DRP1, mitophagy, mitochondrial apoptosis, and neuronal bioenergy imbalance against cerebral I/R injury in both in vitro and in vivo models. Our data also confirmed that ginsenoside CK administration could reduce the binding affinity of Mul1 and Mfn2 to inhibit the ubiquitination and degradation of Mfn2, thereby elevating the protein level of Mfn2 in cerebral I/R injury. Conclusion: These data provide evidence that ginsenoside CK may be a promising therapeutic agent against cerebral I/R injury via Mul1/Mfn2 mediated mitochondrial dynamics and bioenergy.

One-step deep learning-based method for pixel-level detection of fine cracks in steel girder images

Huamei Zhu,Zhihang Li,Mengqi Huang,Pengxuan Ji,Qianbing Zhang 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.1

Identifying fine cracks in steel bridge facilities is a challenging task of structural health monitoring (SHM). This study proposed an end-to-end crack image segmentation framework based on a one-step Convolutional Neural Network (CNN) for pixel-level object recognition with high accuracy. To particularly address the challenges arising from small object detection in complex background, efforts were made in loss function selection aiming at sample imbalance and module modification in order to improve the generalization ability on complicated images. Specifically, loss functions were compared among alternatives including the Binary Cross Entropy (BCE), Focal, Tversky and Dice loss, with the last three specialized for biased sample distribution. Structural modifications with dilated convolution, Spatial Pyramid Pooling (SPP) and Feature Pyramid Network (FPN) were also performed to form a new backbone termed CrackDet. Models of various loss functions and feature extraction modules were trained on crack images and tested on full-scale images collected on steel box girders. The CNN model incorporated the classic U-Net as its backbone, and Dice loss as its loss function achieved the highest mean Intersection-over-Union (mIoU) of 0.7571 on full-scale pictures. In contrast, the best performance on cropped crack images was achieved by integrating CrackDet with Dice loss at a mIoU of 0.7670.

Automatic assessment of post-earthquake buildings based on multi-task deep learning with auxiliary tasks

Huamei Zhu,Zhihang Li,Mengqi Huang,Pengxuan Ji,Hongyu Huang,Qianbing Zhang 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.4

Post-earthquake building condition assessment is crucial for subsequent rescue and remediation and can be automated by emerging computer vision and deep learning technologies. This study is based on an endeavour for the 2nd International Competition of Structural Health Monitoring (IC-SHM 2021). The task package includes five image segmentation objectives - defects (crack/spall/rebar exposure), structural component, and damage state. The structural component and damage state tasks are identified as the priority that can form actionable decisions. A multi-task Convolutional Neural Network (CNN) is proposed to conduct the two major tasks simultaneously. The rest 3 sub-tasks (spall/crack/rebar exposure) were incorporated as auxiliary tasks. By synchronously learning defect information (spall/crack/rebar exposure), the multi-task CNN model outperforms the counterpart single-task models in recognizing structural components and estimating damage states. Particularly, the pixel-level damage state estimation witnesses a mIoU (mean intersection over union) improvement from 0.5855 to 0.6374. For the defect detection tasks, rebar exposure is omitted due to the extremely biased sample distribution. The segmentations of crack and spall are automated by single-task U-Net but with extra efforts to resample the provided data. The segmentation of small objects (spall and crack) benefits from the resampling method, with a substantial IoU increment of nearly 10%.

MRI T2-Weighted Imaging and Fat-Suppressed T2-Weighted Imaging Image Fusion Technology Improves Image Discriminability for the Evaluation of Anal Fistulas

Shi-Ting Feng,Mengqi Huang,Zhi Dong,Ling Xu,Yin Li,Yingmei Jia,Huasong Cai,Bingqi Shen,Zi-Ping Li 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.3

Objective: To explore whether MRI fusion technology (combined T2-weighted imaging [T2WI] and fat-suppressed T2WI [T2WI-FS]) improves signal differences between anal fistulas and surrounding structures. Materials and Methods: A total of 32 patients with confirmed diagnoses of anal fistula were retrospectively studied. All available T2WI and T2WI-FS images for each patient were used to generate fusion image (T2WI-Fusion) based on the addition of gray values obtained from each pixel via an MR post-processing work station. The discriminability of fistula, perianal sphincter, and perianal fat in T2WI, T2WI-FS, and T2WI-Fusion images was quantified with Fisher’s scoring algorithm. For subjective visual image assessment by researchers, five-point scale scores were determined using a modified double-stimulus continuous qualityscale test to evaluate T2WI-FS, T2WI, enhanced axial three-dimensional-volumetric interpolated breath-hold examination (3D-VIBE), and T2WI-Fusion sequence images. The differences were subsequently compared. Results: Mean Fisher scores for fistulas vs. sphincters obtained from T2WI-Fusion (FFusion-fistula = 6.56) were significantly higher than those from T2WI (FT2WI-fistula = 3.35) (p = 0.001). Mean Fisher scores for sphincters vs. fat from T2WI-Fusion (FFusion-sphincter = 10.84) were significantly higher than those from T2WI-FS (FSFS-sphincter = 2.57) (p = 0.001). In human assessment, T2WI-Fusion showed the same fistula discriminability as T2WI-FS, and better sphincter discriminability than T2WI. Overall, T2WI-Fusion showed better discriminability than T2WI, T2WI-FS, and enhanced 3D-VIBE images. Conclusion: T2WI and T2WI-FS fusion technology improves signal differences between anal fistulas and surrounding structures, and may facilitate better evaluation of anal fistulas and sphincters.

Serum MicroRNA Levels as a Noninvasive Diagnostic Biomarker for the Early Diagnosis of Hepatitis B Virus-Related Liver Fibrosis

( Suxia Bao ),( Jianming Zheng ),( Ning Li ),( Chong Huang ),( Mingquan Chen ),( Qi Cheng ),( Kangkang Yu ),( Shengshen Chen ),( Mengqi Zhu ),( Guangfeng Shi ) 대한간학회 2017 Gut and Liver Vol.11 No.6

Background/Aims: To investigate the role of selected serum microRNA (miRNA) levels as potential noninvasive biomarkers for differentiating S0-S2 (early fibrosis) from S3-S4 (late fibrosis) in patients with a chronic hepatitis B virus (HBV) infection. Methods: One hundred twenty-three treatment-naive patients with a chronic HBV infection who underwent a liver biopsy were enrolled in this study. The levels of selected miRNAs were measured using a real-time quantitative polymerase chain reaction assay. A logistic regression analysis was performed to assess factors associated with fibrosis progression. Receiver operating characteristic (ROC) curve and discriminant analyses validated these the ability of these predicted variables to discriminate S0-S2 from S3-S4. Results: Serum miR-29, miR-143, miR-223, miR-21, and miR-374 levels were significantly downregulated as fibrosis progressed from S0-S2 to S3-S4 (p<0.05), but not miR-16. The multivariate logistic regression analysis identified a panel of three miRNAs and platelets that were associated with a high diagnostic accuracy in discriminating S0-S2 from S3-S4, with an area under the curve of 0.936. Conclusions: The levels of the studied miRNAs, with the exception of miR-16, varied with fibrosis progression. A panel was identified that was capable of discriminating S0-S2 from S3-S4, indicating that serum miRNA levels could serve as a potential noninvasive biomarker of fibrosis progression. (Gut Liver 2017;11:860-869)