Experimental study on repair of corroded steel beam using CFRP

Meiling Chen,Sreekanta Das 국제구조공학회 2009 Steel and Composite Structures, An International J Vol.9 No.2

It has been reported that more than thirty five percent of steel bridges in the USA are structurally deficient because of structural degradations. The degraded structures need either full replacement or rehabilitation such that they are able to provide the required services for a longer period of time. The cost for repair in most cases is far less than the cost of replacement. Moreover, repair method generally takes less time than replacement and also reduces service interruption time. Modern advanced composites have been used in aerospace and automotive fields since World War II. In the recent past, because of the high strength-to-weight ratio and high stiffness-to-weight ratio, these composite materials have been introduced to civil engineering infrastructures primarily for repair and rehabilitation of concrete structures. However, only a few preliminary studies on repair of corroded steel structures using theses composite materials are reported in the literature available in the public domain. Thus, in this study, a series of laboratory tests was undertaken to evaluate the effectiveness of this repair method using carbon fiber reinforced polymer composite. The paper discusses the test method and test results obtained from these tests.

Analysis for Stress Characteristics and Structural Parameters Optimization in Orthotropic Steel Box Girders based on Fatigue Performance

Meiling Zhuang,Changqing Miao,Rongfeng Chen 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.6

A fatigue design method for the orthotropic steel deck bridges is proposed. The stress characteristics of welded details are analyzed using the finite element method. Based on the fatigue performance, the structural parameters of the orthotropic steel decks (OSDs) are optimized using the combination BP (back propagation) neural network and genetic algorithms (GA). The calculated results demonstrate that the weld stresses at the deck plate-to-rib, deck plate-to-rib-to-diaphragm welded details are mainly bending stress while those at the rib-to-rib welded details are mainly membrane stress. The fatigue stress of each weld is deeply affected by the transverse and longitudinal direction positions. The local effect of stress distribution of all welded details is remarkable. The calculated results obtained using the proposed model are in good agreement with those obtained using ANSYS and the errors are within 5%. The optimal structural results are highly influenced by the applied wheel loadings, while the optimal results for the deck thickness and the U-rib opening size are highly influenced by temperature. Especially on the ordinary lane, temperature has a great effect on the fatigue performance for all welded details.

Structural State Detection Using Transmissibility and Non-negative Matrix Factorization

Tongqun Ren,Meiling Hui,Junsheng Liang,Dazhi Wang,Liang He,Yonghang Chen 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.11

Transmissibility function (TF) was used in structural state detection which examined the change of the response-only vibration characteristics. The technology of signal correlation was utilized to obtain the TF between two testing points. Multiple TFs under different states were calculated as basic TFs and formed a state matrix. Subsequently, non-negative matrix factorization (NMF) was performed for the state matrix. Then both the basic and testing TFs were projected to the feature subspace derived from NMF so as to obtain the state feature index vectors, respectively. Finally, the Euclidean distance between state feature index vectors was defined as the state indicator. The experimental results indicated that this method can achieve better detection accuracy than that using magnitude indicator. Actually, a result with 100 percent correct detection was achieved when proper rule of dimensionality reduction was selected. This method is essentially a multivariate statistical process monitoring (MSPM) method. It is feasible in vibration-based structural state detection in the situation where the excitation signals are unavailable or inaccessible.

Separation and Characterization of Waste Cotton/polyester Blend Fabric with Hydrothermal Method

Wensheng Hou,Chen Ling,Sheng Shi,Zhifeng Yan,Meiling Zhang,Bonan Zhang,Jinming Dai 한국섬유공학회 2018 Fibers and polymers Vol.19 No.4

In the study, a good separation efficiency of waste cotton/polyester blended fabrics (WBFs) was achieved, with dilute hydrochloric acid as the catalyst under hydrothermal conditions. The morphology and structure of the hydrothermal products including solid and liquid products were characterized by scanning electron microscopy, Fourier transform Infrared spectroscopy, X-ray diffraction, and high-performance liquid chromatography techniques and compared to the untreated polyester and cotton. The results show that the cotton fiber decomposed completely while polyester still retained its fiber characteristics after 3 h of reaction time at 150 oC and 1.5 wt% dilute hydrochloric acid. The hydrolysis of cellulose resulted in a recovery of 96.24 % of the polyester without significant change in its properties; 48.21 % of cellulose powder can be further used as the raw material of microcrystalline cellulose (MCC) and 15.57 % of glucose.

Detail-Enhanced Medical Image Fusion in NSCT Domain

Guocheng Yang,Leiting Chen,Meiling Li 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8

Multimodal medical image fusion technique plays an important role in clinical applications, such as pathologic diagnosis and surgical options. However, many traditional fusion methods cannot well preserve details of source images in the fused image. To address this problem, a detail-enhanced image fusion scheme based on non-subsampled contourlet transform (NSCT) and gain control (i.e., NCGC) is developed in this paper, which can effectively combine the spectral information and the spatial features of source images. The proposed method applies power law transformation to tune coefficients of each decomposed subband, and adjusts the strength of subband signals by smooth gain control. Eventually, the fused image with more anatomical details and functional information is constructed by the inverse NSCT. Three pairs of medical images with different modalities and three fusion metrics are applied to validate the feasibility of this algorithm. Experimental results demonstrate that the proposed method can achieve superior performance in both visual perception and objective assessment.

Liver kinase B1 (LKB1) reduced inflammation and oxidative stress by regulating the AMPK/NLRP3 signaling pathway in LPS-induced lung injury

Yue Yifeng,Zong Liwu,Chen Yongmin,Nianhai Feng,Tang Junxia,Xu Hongyu,Zhao Meiling 대한독성 유전단백체 학회 2021 Molecular & cellular toxicology Vol.17 No.4

Background Inflammation and oxidative stress-induced molecular death are one of the important causes for lung injury in critically ill patients. LKB1 is an important protein kinase in the body and has regulated inflammation and oxidative stress. However, LKB1 control inflammation and oxidative stress in lung injury were unclear. Objective We aimed to investigate the function and mechanism of Liver kinase B1 (LKB1) in lipopolysaccharide (LPS)-induced lung injury. Result LKB1 prevented lung injury, and weakened correlation oxidative stress and inflammatory reaction in LPS-induced mice model of lung injury. Up-regulation of LKB1 reduced reactive oxygen species (ROS) production and it-induced oxidative stress, and weakened inflammatory reactions in LPS-induced lung injury A549 cells. Down-regulation of LKB1 increased ROS production and it-induced oxidative stress, and enhanced inflammatory reactions in LPS-induced lung injury A549 cells. LKB1 induced phosphorylation (p)-AMPK protein expression, and suppressed the protein expression of NLRP3 in LPS-induced mice model of lung injury and in LPS-induced lung injury A549 cells. This experiment demonstrated the inhibition of AMPK or activation of NLRP3 inflammasome reversed the anti-inflammation function of LKB1 in LPS-induced lung injury. Meanwhile, ROS-induced oxidative stress also participated in the anti-inflammation effects of LKB1 in LPS-induced lung injury. Conclusion Therefore, our results indicate that LKB1 reduced inflammation and oxidative stress by regulating the AMPK/NLRP3 signaling pathway in LPS-induced lung injury.

Nonparaxial Propagation of Rotating Cosh-Gaussian Beams

Dongmei Deng,Xi Peng,Chidao Chen,Bo Chen,Yulian Peng,Meiling Zhou 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.5

Starting from the inhomogeneous Helmholtz equation, we obtain the exact rotating Cosh-Gaussian vector potential solution oriented along the propagation axis (i.e., the z axis). The electricand the magnetic fields are both expressed in terms of rotating Cosh-Gaussian beams (RCGBs) thatare rigorous solutions to Maxwell’s equations. The paraxial and the nonparaxial RCGBs have aninherent rotating property in that the angular velocity decreases with increasing the propagationdistance. The evolution of the Poynting vector of the RCGBs is analyzed as they propagate in freespace.

A New Modulation to Eliminate the Impact of Overlap Time for Three-Phase Current Source Converters

Ding Hao,Guo Xiaoqiang,He Meiling,Shi Changli,Jia Dongqiang,Chen Chao,Guerrero Josep M. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

Three-phase current source converter tends to be attractive in future industrial applications. In order to ensure the continuous current for the dc-link inductor of the current source converter (CSC), an overlap time is mandatory for each switch, so as to avoid the over-voltage spike caused by the dc-link inductor current interruption. However, the overlap time results in the undesirable harmonics and current distortion, which fails to comply with the relevant IEEE Standard in terms of power quality. Especially, the negative infl uence caused by overlap time eff ect is much more serious with the increasing of the switching frequency applied to CSC. In order to solve the problem, the impact of the overlap time on the CSC is investigated, and the error resulted from the overlap time is clearly demonstrated. Based on the pulse equivalent principle and the Fourier analysis, the quantitative relationship between the current harmonic and the overlap time is obtained. And then, a new approach to eliminate the impact of overlap time on the CSC is proposed. Finally, the simulation and experimental results are carried out to verify the eff ectiveness of the proposed solution.

A study on tensile strength mechanism of hypoeutectic gray cast iron reinforced by composite silicon carbide powder

Chunfeng Wang,Jun Yang,Guilin Liu,Hong Gao,Meiling Chen 한양대학교 세라믹연구소 2022 Journal of Ceramic Processing Research Vol.23 No.4

This study aims to reveal the changes in the microstructure of hypoeutectic gray cast iron under the addition of compositesilicon carbide powder of different mass fractions, and to explore how modified silicon carbide (SiC) particles of different sizesand contents improve the mechanical properties of hypoeutectic gray cast iron. The results showed that the modified SiCparticles increased the nucleation, the undercooling and microstructure of hypoeutectic gray cast iron, and the tensile strengthof the iron at room temperature was increased by 18,28%. The present work solves the problem that traditional SiC ceramicparticles are prone to agglomeration in molten metal, analyzes its action mechanism, and can expand the application of SiCceramic particles to strengthening metal properties of casting materials.

Add-on Tiotropium in Chinese Patients With Moderate Asthma: A Pooled Subgroup Analysis of MezzoTinA-Asthma 1 and 2

Jiangtao Lin,Huanying Wan,Jian Kang,Qianli Ma,Ping Chen,Meiling Jin,Haoyan Wang,Shuang Liu,Qinglin Hao,Yong Lin,Lin Su,Na Hu 대한천식알레르기학회 2019 Allergy, Asthma & Immunology Research Vol.11 No.4

Purpose: Asthma affects approximately 30 million patients in China; however, tiotropium data for Chinese patients is limited. This study aimed to assess the efficacy and safety of tiotropium in Chinese patients with moderate symptomatic asthma. Methods: A post hoc subgroup analysis was conducted on 430 Chinese patients pooled from two 24-week, replicate phase 3 trials (NCT01172808 and NCT01172821), in which they received once-daily tiotropium 2.5 μg (Tio R2.5) or 5 μg (Tio R5) (n = 106 or 109, respectively), twice-daily salmeterol 50 μg (Sal 50) (n = 110), or placebo (n = 105), while maintaining inhaled corticosteroids (ICS). The co-primary endpoints assessed in week 24 were forced expiratory volume in 1 second (FEV1) peak0–3h response, trough FEV1 response, and responder rate as assessed using the Asthma Control Questionnaire (ACQ). Results: For both FEV1 peak0–3h responses and trough FEV1 responses, the mean treatment differences were greater for Tio R2.5, Tio R5, and Sal 50 compared with placebo at 0.249 L, 0.234 L, and 0.284 L, and 0.172 L, 0.180 L, and 0.164 L, respectively (P< 0.001). The ACQ responder rate in placebo, Tio R2.5, Tio R5, and Sal 50 was 58.7%, 62.3%, 59.3%, and 69.1%, respectively. Furthermore, 11 (2.6%) of 430 patients had serious adverse events (Tio R5, n = 4; Tio R2.5, n = 1; Sal 50, n = 1; and placebo, n = 5). Conclusions: Once-daily tiotropium, as add-on to medium-dose ICS, was effective and well tolerated for Chinese patients with moderate symptomatic asthma, consistent with the main analysis.