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Reliability-based sensitivity of mechanical components with arbitrary distribution parameters
Yimin Zhang,Xiangdong He,Zhou Yang,Qiaoling Liu,Bangchun Wen 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.6
This paper presents a reliability-based sensitivity method for mechanical components with arbitrary distribution parameters. Techniques from the perturbation method, the Edgeworth series, the reliability-based design theory, and the sensitivity analysis approach were employed directly to calculate the reliability-based sensitivity of mechanical components on the condition that the first four moments of the original random variables are known. The reliability-based sensitivity information of the mechanical components can be accurately and quickly obtained using a practical computer program. The effects of the design parameters on the reliability of mechanical components were studied. The method presented in this paper provides the theoretic basis for the reliability-based design of mechanical components.
Image-based Visual Servoing using Improved Image Moments in 6-DOF Robot Systems
Yimin Zhao,Wen-Fang Xie,Sining Liu 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.3
This paper addresses the challenges of choosing proper image features for planar symmetric shape objects and designing visual servoing controller to enhance the tracking performance in image-based visual servoing (IBVS). Six image moments are chosen as the image features and the analytical image interaction matrix related to the image features are derived. A controller is designed to efficiently increase the robustness of the visual servoing system. Experimental results on a 6-DOF robot visual servoing system are provided to illustrate the effectiveness of the proposed method.
Chunyu Zhao,Qinghua Zhao,Yimin Zhang,Bangchun Wen 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.1
In the average method of modified small parameters, the synchronization of two coupled exciters is converted to a problem on the existence and stability of zero solutions for the average differential equations of small parameters over the average period of two exciters. To implement frequency capture, the torque of frequency capture should be greater than or equal to the absolute value of the difference between the residual electromagnetic torques of the two motors. Because each exciter is involved in the motion of the vibrating system it has excited, its relative moment of inertia is reduced. The reduction is proportional to half its coefficient of cosine effect of phase angles (CCEPA). Because one of the exciters is involved in the motion excited by the other, a coupled moment of inertia exists for the two exciters. The stability of the synchronization of the two exciters is affected by the reduction of their relative moments of inertia and their moment of coupling inertia. For the synchronization to be stable, two conditions must be satisfied: (1) the non-dimensional relative moments of inertia of the two exciters are all greater than zero, and (2) four times the product of their non-dimensional relative moments is greater than the square of the coefficient of coupled cosine effect (CCCPA). The stability of synchronization depends solely on the ratios of the masses of the two exciters to the mass of the vibrating system and the ratio of the distance between one exciter and the centroid of the rigid frame to the equivalent rotating radius of the vibrating system about its centroid of the rigid frame, and is independent of the parameters of the two induction motors.
MOPSO-based Data Scheduling Scheme for P2P Streaming Systems
( Pingshan Liu ),( Yaqing Fan ),( Xiaoyi Xiong ),( Yimin Wen ),( Dianjie Lu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.10
In the Peer-to-Peer (P2P) streaming systems, peers randomly form a network overlay to share video resources with a data scheduling scheme. A data scheduling scheme can have a great impact on system performance, which should achieve two optimal objectives at the same time ideally. The two optimization objectives are to improve the perceived video quality and maximize the network throughput, respectively. Maximizing network throughput means improving the utilization of peer’s upload bandwidth. However, maximizing network throughput will result in a reduction in the perceived video quality, and vice versa. Therefore, to achieve the above two objects simultaneously, we proposed a new data scheduling scheme based on multi-objective particle swarm optimization data scheduling scheme, called MOPSO-DS scheme. To design the MOPSO-DS scheme, we first formulated the data scheduling optimization problem as a multi-objective optimization problem. Then, a multi-objective particle swarm optimization algorithm is proposed by encoding the neighbors of peers as the position vector of the particles. Through extensive simulations, we demonstrated the MOPSO-DS scheme could improve the system performance effectively.
Structure effect of a suction pipe on slag-discharging performance in a shaft boring machine
Hejia Jiang,Laikuang Lin,Zhongbao Wen,Xuemeng Xiao,Zixiong Zhou,Yimin Xia 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9
The efficiency and stability of shaft boring machines depend critically on the slag-discharging system. In this study, we simulate the slagging process by using the coupled computational fluid dynamics/discrete element method and validate the method’s reliability through experiments. We investigate the impact of outlet diameter, inlet diameter, and outlet section length on slag-discharging performance. We establish the slag-discharging principle of the suction pipe by analyzing the particle motion trajectory. The flow field close to the suction pipe can be classified into collecting and lifting zones on the basis of the main flow direction velocity. Furthermore, we propose pipes with seven typical types, among which the straightconical type exhibits the most favorable slag-discharging performance. The straight-conical pipe enhances the slag-discharging mass by 22.49 % compared with the straight pipe.