Study on New Anti-drop-beam Device of High-speed Railway Bridge in High Intensity Seismic Region

Jun Dong,Dan Leng 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Falling beam is one of the most common seismic damages for high-speed railway bridges, and it influences the running safety of trains. To prevent falling beam and then ensure the running safety of trains, a new anti-drop-beam device is developed for high-speed railway bridge in high intensity seismic regions in this paper. Firstly, the formulas are derived through the theoretical analysis to calculate mechanical parameters and force-displacement constitutive relation of device. Secondly, two groups of experiments are carried out to study mechanical performance of device and validated derived formulas. Finally, the finite element model of a high-speed railway continuous bridge is established to study seismic performance of device. The results show that the derived formulas can accurately calculate mechanical parameters and force-displacement constitutive relation of device. The energy dissipation capacity and low-cycle fatigue performance of device are good. The device can effectively limit the beam end displacement and well dissipate seismic energy under earthquakes, and it can be applied in engineering practice.

APMDI-CF: An Effective and Efficient Recommendation Algorithm for Online Users

Ya-Jun Leng,Zhi Wang,Dan Peng,Huan Zhang 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.11

Recommendation systems provide personalized products or services to online users by mining their past preferences. Collaborative filtering is a popular recommendation technique because it is easy to implement. However, with the rapid growth of the number of users in recommendation systems, collaborative filtering suffers from serious scalability and sparsity problems. To address these problems, a novel collaborative filtering recommendation algorithm is proposed. The proposed algorithm partitions the users using affinity propagation clustering, and searches for k nearest neighbors in the partition where active user belongs, which can reduce the range of searching and improve real-time performance. When predicting the ratings of active user’s unrated items, mean deviation method is used to impute values for neighbors’ missing ratings, thus the sparsity can be decreased and the recommendation quality can be ensured. Experiments based on two different datasets show that the proposed algorithm is excellent both in terms of real-time performance and recommendation quality.

Effect of bridge lateral deformation on track geometry of high-speed railway

Hongye Gou,Longcheng Yang,Dan Leng,Yi Bao,Qianhui Pu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.2

This paper presents an analytical model to analyze the mapping relationship between bridge lateral deformation and track geometry of high-speed railway. Based on the rail deformation mechanisms, the deformation of track slab and rail at the locations of fasteners are analyzed. Formulae of rail lateral deformation are derived and validated against a finite element model. Based on the analytical model, a rail deformation extension coefficient is presented, and effects of different lateral deformations on track geometry are evaluated. Parametric studies are conducted to evaluate the effects of the deformation amplitude, fastener stiffness and mortar layer stiffness on the rail deformation. The rail deformation increases with the deformation of the girder, and is dependent on the spacing of the fasteners, the elastic modulus of the rail's material, and the moment of inertia of the rail's section.

Study on Magnetic Force Calculation of Spherical Permanent Magnets

Yuyang Zhang,Yonggang Leng,Dan Tan,Jinjun Liu Korean Magnetics Society 2018 Journal of Magnetics Vol.23 No.4

This paper presents three approaches to calculate the interacting magnetic force about spherical permanent magnet, respectively based on magnetic dipole-dipole model, equivalent magnetic charge model and equivalent magnetizing current model. We use all of three models to fully calculate and study the behaviors of lateral and axial forces with respect to the related positions between a pair of spherical magnets. The accuracies of the calculation results are compared with the experimental data. In conclusion, the magnetic dipole-dipole model has the most advantageous accuracy and efficiency for the magnetic force calculation about spherical permanent magnets on account of the particularity of sphere. Our study provides an important criterion for choosing a proper method to calculate magnetic force about spherical permanent magnet.

Comparison of Magnetic Force Calculation on Permanent Magnets with Models of Equivalent Magnetic Charge and Magnetizing Current

Yuyang Zhang,Yonggang Leng,Jinjun Liu,Dan Tan 한국자기학회 2019 Journal of Magnetics Vol.24 No.3

Accurate magnetic force calculation is essential to effectively analyzing a system or device containing magnets. Among several approaches used in the interacting magnetic force calculation of permanent magnets, equivalent magnetic charge and equivalent magnetizing current models are widely adopted. In this paper, we choose cubes and cylinders as calculating objects to investigate the detailed calculation procedures. Higher calculation accuracy of the equivalent magnetizing current model is verified by comparison between simulation and experiment results. Furthermore, we analyze the relations between two models and discriminate their equivalence in the magnetic force calculation respectively at both micro and macro scale. Reference basis for choosing a proper model to calculate magnetic force is provided in this work, which is beneficial for the design of electro-mechanical structures with permanent magnets.

Comparison of Epidermal Growth Factor Receptor Mutations between Primary Tumors and Lymph Nodes in Non-small Cell Lung Cancer: a Review and Meta-analysis of Published Data

Wang, Feng,Fang, Ping,Hou, Dan-Yang,Leng, Zai-Jun,Cao, Le-Jie Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.11

Background: Epidermal growth factor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) can predict the clinical response to tyrosine kinase inhibitor (TKI) therapy. However, EGFR mutations may be different in primary tumors (PT) and metastatic lymph nodes (MLN). The aim of this study was to compare EGFR mutations between PT and the corresponding MLN in NSCLC patients, and provide some guidelines for clinical treatment using TKI therapy. Materials and Methods: A systematic review and meta-analysis was performed with several research databases. Relative risk (RR) with the 95% confidence interval (CI) were used to investigate the EGFR mutation status between PT and the corresponding MLN. A random-effects model was used. Results: 9 publications involving 707 patients were included in the analysis. It was found that activation of EGFR mutations identified in PT and the corresponding MLN was 26.4% (187/707) and 19.9% (141/707), respectively. The overall discordance rate in our meta-analysis was 12.2% (86/707). The relative risk (RR) for EGFR mutation in PT relative to MLN was 1.33 (95%CI: 1.10-1.60; random-effects model). There was no significant heterogeneity between the studies ($I^2$=5%, p=0.003). Conclusions: There exists a considerable degree of EGFR mutation discrepancy in NSCLC between PT and corresponding MLN, suggesting that tumor heterogeneity might arise at the molecular level during the process of metastasis.

Enhanced fermentative γ-aminobutyric acid production by a metabolic engineered Corynebacterium glutamicum

Jingbai Wen,Wanli Sun,Guihua Leng,Dan Li,Changyan Feng,Zhide Tian,Xin Wang 한국생물공학회 2024 Biotechnology and Bioprocess Engineering Vol.29 No.1

γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid with important physiological functions, which has been widely used in food, pharmaceuticals, and polyamides production. The fermentative GABA production by Corynebacterium glutamicum was recognized as one of the most promising methods. However, the problems of low catalytic activity of the heterologously expressed glutamate decarboxylase (GAD) and the imbalanced carbon fl ux between cell growth and GABA synthesis severely limited the GABA production by C. glutamicum . This study applied combinational metabolic engineering and catalytic condition optimization strategies to solve these two major obstacles. The secretory expression of GAD was enhanced using a bicistronic-designed expression cassette. This bicistronic expression cassette was further triply inserted into the genome by substituting the ldhA , pqo , and ack genes, thus stabilizing the expression of GAD and reducing the accumulation of by-products of lactate and acetate. A growth-regulated promoter P CP_2836 was applied to dynamically control the expression of odhA , thus controlling the α-oxoglutarate dehydrogenase complex activity for balanced cell growth and GABA production. The glutamate precursor synthesis and pyridoxal 5′-phosphate supply were also strengthened by promoter substitution. Finally, through a two-stage pH-controlled fed-batch fermentation under optimized conditions, the engineered strain reached GABA titer of 81.31 ± 1.31 g/L with a yield and productivity of 0.50 ± 0.01 g/g and 1.36 ± 0.23 g L −1 h −1 , which was 4.8%, 13.6%, and 11.2% higher than that of the original strain. This study laid a solid foundation for industrial fermentative GABA production by engineered C. glutamicum .