A dependent stress–strength interference model based on mixed copula function

Jianxiong Gao,Zongwen An,Bo Liu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10

In the traditional Stress–strength interference (SSI) model, stress and strength must satisfy the basic assumption of mutual independence. However, a complex dependence between stress and strength exists in practical engineering. To evaluate structural reliability under the case that stress and strength are dependent, a mixed copula function is introduced to a new dependent SSI model. This model can fully characterize the dependence between stress and strength. The residual square sum method and genetic algorithm are also used to estimate the unknown parameters of the model. Finally, the validity of the proposed model is demonstrated via a practical case. Results show that traditional SSI model ignoring the dependence between stress and strength more easily overestimates product reliability than the new dependent SSI model.

Improved Particle Swarm Optimization Algorithm for Adaptive Frequency-Tracking Control in Wireless Power Transfer Systems

Yang Li,Liu Liu,Cheng Zhang,Qingxin Yang,Jianxiong Li,Xian Zhang,Ming Xue 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

Recently, wireless power transfer (WPT) via coupled magnetic resonances has attracted a lot of attention owing to its long operation distance and high efficiency. However, the WPT systems is over-coupling and a frequency splitting phenomenon occurs when resonators are placed closely, which leads to a decrease in the transfer power. To solve this problem, an adaptive frequency tracking control (AFTC) was used based on a closed-loop control scheme. An improved particle swarm optimization (PSO) algorithm was proposed with the AFTC to track the maximum power point in real time. In addition, simulations were carried out. Finally, a WPT system with the AFTC was demonstrated to experimentally validate the improved PSO algorithm and its tracking performance in terms of optimal frequency.

Characteristics of vibration response of ball bearing with local defect considering skidding

Yu Tian,Changfeng Yan,Yaofeng Liu,Wei Luo,Jianxiong Kang,Zonggang Wang,Lixiao Wu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

The occurrence and aggravation of local defects in ball bearings are closely linked to the skidding behavior of the ball. Previous studies have given less attention to investigating the impact of localized defects on the problem of bearing skidding. To investigate the dynamic response of defective bearings due to skidding, a dynamic model of the ball bearing is developed that considers various factors, including self-rotation, revolution, and radial motion of the ball, as well as the contact forces and friction forces of ball/cage and ball/race, time-varying displacement excitation, and elastohydrodynamic lubrication (EHL). Experimental signals collected from a machinery fault simulator test rig are used to validate the accuracy of the proposed model. The impact of race defects on the vibration characteristics of the bearing is analyzed, and the patterns of variation in contact and friction forces within one cycle of inner race rotation are described. The results indicate that the presence of defects intensifies the force fluctuation of the ball and causes it to deviate from its normal rolling condition. By comparing the skidding characteristics of a healthy bearing with a defective one under slippage, local defects will increase the skidding ratio of bearings. The proposed model can investigate the impact of race defects on the vibration response of ball bearings under the skidding condition.

Task Offloading of Intelligent Building Based on CO–HHO Algorithm in Edge Computing

Yi Lingzhi,Gao Xieyi,Li Zongpin,Feng Xiaodong,Huang Jianxiong,Liu Qiankun 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

With the rapid development of intelligent devices, the intelligence of buildings is becoming more and more obvious, which leads to the rapid growth of data generated by building users. The existing network bandwidth is far from enough for the transmission of existing data, which will lead to congestion in the process of data transmission. In this paper, a task offl oading strategy based on edge computing is proposed. The edge server is deployed near the data source, which mainly solves the problems of transmission delay and energy consumption of building users during task offl oading. In this paper, the mathematical model of system delay and energy consumption is established fi rst. In order to better refl ect the quality of the system, the delay and energy consumption are combined into system utility, and then the objective function is established. Since the objective function is a mixed integer nonlinear programming problem, fi nding the optimal solution usually requires exponential time complexity. Therefore, this paper fi rstly uses the Tammer decomposition method to decouple the objective function, and decomposes it into the resource allocation problem of fi xed task offl oading decision and the task offl oad problem of maximizing the objective function. Then the convex optimization (CO) theory is used to greatly reduce the complexity of the objective function and optimize the resource allocation problem. Finally, the task offl oading problem is solved by the improved Harris Hawks Optimization (HHO) . The paper compares various offl oading schemes. The simulation results show that the CO–HHO offl oading strategy based on edge computing proposed in this paper can eff ectively reduce the transmission delay and energy consumption of user tasks in intelligent buildings, and is superior to others in all aspects.

Enhanced recovery after surgery strategy for cirrhosis patients undergoing hepatectomy: experience in a single research center

Yiling Zheng,Liming Wang,Fan Wu,Weiqi Rong,Yunhe Liu,Kai Zhang,Jianxiong Wu 대한외과학회 2020 Annals of Surgical Treatment and Research(ASRT) Vol.98 No.5

Purpose: To evaluate the safety and effectiveness of an enhanced recovery after surgery (ERAS) programme after curative liver resection in cirrhotic hepatocellular carcinoma (HCC) patients. Methods: One hundred sixty-two patients were enrolled in the study; 80 patients whose data were collected prospectively were assigned to the ERAS group, and 82 patients whose data were collected retrospectively were assigned to the control group. Preoperative clinicopathologic factors, surgical factors, and postoperative outcomes of the 2 groups were compared. Logistic regression was applied to explore potential predictors of hospital stay and morbidity. Results: The postoperative hospital stay, postoperative complication rate, and recovery of liver function on postoperative day 5 seemed to be better in the ERAS group. The composition of complications was different in the 2 groups; pleural effusion and postoperative ascites were more common in the control group, and indocyanine green retention at 15 minutes, operation time, preoperative alanine aminotransferase, and number of liver segmentectomies were associated with postoperative complications rather than ERAS intervention. Conclusion: The ERAS programme is safe and effective for HCC patients with chronic liver disease undergoing hepatectomy, but it seems that surgical factors, such as operation type, have a greater impact on morbidity than other factors. Operative characteristics such as the method of blood loss control and the volume of liver resection should be augmented into ERAS protocol of hepatectomy.

One-Step Engineering of a Stable, Selectable Marker-Free Autoluminescent Acinetobacter baumannii for Rapid Continuous Assessment of Drug Activity

( Huofeng Jiang ),( Yamin Gao ),( Sheng Zeng ),( Shuai Wang ),( Zhizhong Cao ),( Yaoju Tan ),( Huancai Yin ),( Jianxiong Liu ),( Tianyu Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.9

The rising cases of multidrug-resistant Acinetobacter baumannii (Ab) and the lack of effective drugs call for quick attention. Here, based on a Tn7 transposon and Xer/dif system, we constructed a stable, selectable marker-free autoluminescent Ab capable of producing visible light without extra substrates. Utilization of this autoluminescent reporter strain has the potential to reduce the time, effort and costs required for the evaluation of activities of anti-Ab drug candidates in vitro.