Reliability-based assessment of high-speed railway subgrade defect

Qingsong Feng,Kui Sun,Hua-peng Chen 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.2

In this paper, a dynamic response mapping model of the wheel-rail system is established by using the support vector regression (SVR) method, and the hierarchical safety thresholds of the subgrade void are proposed based on the reliability theory. Firstly, the vehicle-track coupling dynamic model considering the subgrade void is constructed. Secondly, the subgrade void area, the subgrade compaction index K30 and the fastener stiffness are selected as random variables, and the mapping model between these three random parameters and the dynamic response of the wheel-rail system is built by using the orthogonal test and the SVR. The sensitivity analysis is carried out by the range analysis method. Finally, the hierarchical safety thresholds for the subgrade void are proposed. The results show that the subgrade void has the most significant influence on the carbody vertical acceleration, the rail vertical displacement, the vertical displacement and the slab tensile stress. From the range analysis, the subgrade void area has the largest effect on the dynamic response of the wheel-rail system, followed by the fastener stiffness and the subgrade compaction index K30. The recommended safety thresholds for the subgrade void of level I, II and III are 4.01m2, 6.81m2 and 9.79m2, respectively.

Low Chattering Trajectory Tracking Control of Non-singular Fast Terminal Sliding Mode Based on Disturbance Observer

Jiqing Chen,Chaoyang Zhao,Qingsong Tang,Xu Liu,Zhikui Wang,Chengzhi Tan,Jiahua Wu,Teng Long 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified. The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified.

The Introduction of CHED Teaching Methods We Used IN the TB Training

Jie XING,Qingsong CHEN 한국환경보건학회 2004 한국환경보건학회 학술대회 자료집 Vol.2004 No.-

An Improved Energy Recovery Clamp Circuit for PWM Converters with a Wide Range of Input Voltage

Honnyong Cha,Lihua Chen,Fang Z. Peng,Qingsong Tang 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

A full-bridge dc-dc converter employing diode rectifier in the output experiences severe voltage overshoot and oscillation problem across the diode rectifier caused by the interaction between the junction capacitance of the rectifier diode and the leakage inductance of transformer. The pronounced reverse-recovery current of high power diodes enforces these issues significantly by increasing power loss and voltage overshoot. Conventional energy recovery clamping circuits suffer from high voltage overshoot if the input voltage of converter is wide. In this work, a novel energy recovery clamp circuit is proposed to overcome this problem. Performance of the proposed circuit is verified both theoretically and experimentally with a 70 ㎾ dc-dc converter.

Propagation characteristics of ultrasonic guided waves in tram rails

Kui Sun,Hua-peng Chen,Qingsong Feng,Xiaoyan Lei 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.4

Ultrasonic guided wave testing is a very promising non-destructive testing method for rails, which is of great significance for ensuring the safe operation of railways. On the basis of the semi-analytical finite element (SAFE) method, a analytical model of 59R2 grooved rail was proposed, which is commonly used in the ballastless track of modern tram. The dispersion curves of ultrasonic guided waves in free rail and supported rail were obtained. Sensitivity analysis was then undertaken to evaluate the effect of rail elastic modulus on the phase velocity and group velocity dispersion curves of ultrasonic guided waves. The optimal guided wave mode, optimal excitation point and excitation direction suitable for detecting rail integrity were identified by analyzing the frequency, number of modes, and mode shapes. A sinusoidal signal modulated by a Hanning window with a center frequency of 25 kHz was used as the excitation source, and the propagation characteristics of high-frequency ultrasonic guided waves in the rail were obtained. The results show that the rail pad has a relatively little influence on the dispersion curves of ultrasonic guided waves in the high frequency band, and has a relatively large influence on the dispersion curves of ultrasonic guided waves in the low frequency band below 4 kHz. The rail elastic modulus has significant influence on the phase velocity in the high frequency band, while the group velocity is greatly affected by the rail elastic modulus in the low frequency band.

趙昌家世及其與傳教士的往來

陳青,松(Chen Qingsong) 경북대학교 아시아연구소 2009 아시아연구 Vol.- No.6

趙昌은 청의 강희(康熙)․옹정(雍正)시기 궁정에서 하나의 미미한 인물이었지만, 그 강희(康熙)․옹정(雍正) 양 왕조에서의 상황은 큰 차이가 있다. 康熙8년 시기 조창은 康熙帝를 주변에서 모셨는데 당시 그는 12, 13세의 소년에 불과하였다. 현존하는 문헌을 살펴보면, 조창은 오랫동안 養心殿에서 복무하면서 康熙帝의 호위를 담당하였고, 이후 養心殿監造를 역임하였다. 그는 康熙帝가 駕崩할 때까지 養心殿에서 직무를 담당했다. 그가 맡은 주요직책은 서양인과 관련있는 것으로 그는 몇 개의 외국어를 알았다. 이외에도 그는 일상적인 養殿업무를 관리하고 방화기를 시험하거나 책을 만드는 일에도 참여하였다. 옹정(雍正)이 즉위한 후 얼마 지나지 않아, 조창은 가산을 몰수당하는 운명을 맞이했을 뿐만 아니라, 감옥에 끌려가 결국 옥중에서 세례를 받고 사망하였다. 조창은 장기간에 걸쳐 선교사와 왕래하였고, 중국에서 선교사의 활동을 개선하기 위하여 노력하였다. 예를 들면 그는 “容教詔令”의 통과를 추진하였고, 로마교황의 사절인 多羅와 嘉樂등의 접대활동에 참여하면서 서방 세계에 그의 명성을 알리게 되었다. 당시 그와 관련된 선교사들의 태도는 매우 달랐다. 대부분의 예수회의 사람들은 그에게 감격과 찬양을 한데 비하여, 선교 방법이 다른 馬國賢등의 예수회의 사람들은 불만을 노골적으로 표시하는 것을 통해 당시 선교사들 사이에는 모순과 대립이 있었다는 것을 알 수 있다. 지금까지 그의 인생에서 한두 가지가 잘못 전해지면서 어떤 사람은 그가 환관이라고 하고, 어떤 사람은 옹정(雍正)이 즉위한 직후 피살되었다고 하는 등 여전히 명확하지 않다. During the reign time of Kangxi and Yongzheng of Qing dynasty, Zhaochang is a very tiny figure in the Court. However, there was a huge difference to him between the time of the two emperors. In the eight year of Kangxi, when Zhaochang just was twelve or thirteen years old, he had already served Kangxi as Imperial Bodyguard and mourned for Jean Adam Schall Von Beli in front of his grave. From that time, according to the found records, Zhaochang was in Yangxin Dian and worked for Kangxi. He got kown some foreign languages, and conncetting with the foreignors was his major job. His long-term contacted with the missionary made him quite well known in the West. It was regrettable that the missionaries’ attitude about him was completely different. We also could see missionaries internal contradictions from that. It is that person, now, whose figure is more incorrectly because of some erroneous messages. He did not even a clear outline.

A Self-adaptive Workload Balancing Algorithm on GPU Clusters

Jianjiang Li,Yajun Liu,Peng Zhang,Qingsong Miao,Lei Zhang,Wei Chen 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.11

With the wide application of GPU in High Performance Computing, more and more heterogeneous CPU+GPU clusters have been establishedin many fields. But with the comprehensive using of heterogeneous CPU+GPU clusters, workload balancing has become an important problem when the process nodes coordinate with each other, and the execution time of a program on imbalanced clusters resides on the slowest node. Although there are many strategies and algorithms that can solve the problem of workload balancing to some extent, they generally face the problem of high consumption of communication caused by the task migration. In order to make up for the existing deficiencies, this paper proposes a virtual task migration algorithm adapted to GPU clusters on CUDA platform. This algorithm uses virtual task migration to avoid actual data transmission between nodes, so the communication overhead is obviously decreased. At last, this paper performs an actual test using matrix multiplication to verify this algorithm. The experiment results show that compared with static task partitioning, the algorithm proposed in this paper can effectively achieve dynamic workload balancing and reduce the execution time of programs on GPU clusters, thus the algorithm can significantly improve program execution performance of GPU clusters on CUDA platform.

Discussion on the Path of Improving College Students Ideological and Political Quality under the Background of Patriotism Education

Hu Lamei(胡腊,梅),Feng Jieming(冯,洁,铭,),Li Qingsong(李青,嵩),Chen Lu(陈,璐,) 아시아사회과학학회 2022 International Science Research Vol.2 No.1

去年是建党一百周年, 借着开展党史学习教育的契机, 让更多的大学生了解党的历史, 在全校范围内开展爱国主义教育, 对于提升学生的思想政治素质是很有效的。因此在全社会大力开展爱国主义教育的大背景下, 对如何提升大学生思想政治素质进行分析和研究至关重要。本文基于爱国主义教育大背景下, 就如何提升大学生思想政治素质的路径进行探讨, 并提出具体可实施的建议。 Last year is the one hundredth anniversary of the founding, through to carry out the party history study chance in education, let more students understand the party s history, to carry out patriotism education in the school, to improve students ideological and political quality, it is very effective So vigorously carry out patriotism education in the whole society s big background, how to improve college students ideological and political quality is very important to analyze and study Based on the background of patriotism education, this paper discusses how to improve the ideological and political quality of college students, and puts forward concrete feasible suggestions.

Fatty acid-binding protein 5 activates cyclooxygenase-2 and promotes hypoxic injury in LO2 cells

Pan Long,Pang Yihan,Xiao Heng,Deng Xin,Chen Qingsong 대한독성 유전단백체 학회 2022 Molecular & cellular toxicology Vol.18 No.1

Background Hepatic hypoxia always results in liver inflammation and dysfunction. Fatty acid-binding protein 5 (FABP5) has been reported as a hypoxia-inducible gene and a regulator of inflammatory reaction . Objective To evaluate the effects of FABP5 on hypoxic liver injury and its potential mechanisms. Results FABP5 was hypoxia-inducible expression in liver tissues and LO2 cells. The expression levels of IL6 and TNFα were upregulated with the increasing expression of FABP5 in LO2 cells. Downregulation of FABP5 expression decreased the expression levels of ALT, AST and increased cell viability of hypoxic LO2 cells. Downregulation of FABP5 expression inhibited the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway and decreased inflammatory reaction in hypoxic LO2 cells. Conclusions FABP5 was shown to activate COX-2/PGE2 pathway and promote hypoxic injury in LO2 cells. FABP5 may be a potential target for the treatment of hypoxic liver injury.

Effect of Ion Source Current on the Microstructure and Properties of Cr-DLC Coatings Prepared by Ion Beam-Assisted Arc Ion Plating

Yao Cai,Huidong Liu,Ye Ma,Qiang Wan,Hao Cheng,Yan Liu,Yanming Chen,Qingsong Mei,Bing Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

Cr-containing diamond-like carbon (Cr-DLC) nanocomposite coatings were synthesized by ion beam-assisted arc ion plating with varying hollow cathode ion source (HCIS) currents. The morphologies, compositions and microstructures were characterized by scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-Ray photoelectron spectrometer (XPS), Raman spectroscopy, grazing incidence X-ray diffraction (GIXRD) and high-resolution transmission electron microscopy (HRTEM). Hardness and friction coefficient were investigated by using nanoindentation and ball-on-disc tribometer, respectively. With no HCIS current, the coating exhibits the maximal growth rate and a rough surface, as well as lower hardness and elastic modulus. With the increasing HCIS current from 40 A to 80 A, the growth rate and the content of chromium carbide decrease obviously, the sp3/sp2 ratio increases initially to the maximum at the HCIS current of 60 A, the highest hardness and elastic modulus are obtained at the HCIS current of 50 A. It is also revealed that moderate HCIS current can reduce surface roughness obviously and promote tribological properties. The correlation of the HCIS current with the microstructure and performance of Cr-DLC coating has been established.