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Modified breathing mechanism model and phase waterfall plot diagnostic method for cracked rotors
Jingsong Xie,Wei Cheng,Yanyang Zi 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6
Transverse breathing cracks are a primary damage mode in rotor systems and seriously influence the safety and reliability of equipment operation. The vibration characteristics exhibited by cracked rotors when passing through critical speeds serve as important evidence in the diagnosis of cracks, and a breathing mechanism model without weight dominance is needed to study these resonant characteristics. In this work, a restoring force modified model is proposed for studying the breathing mechanism of cracked Jeffcott rotors without weight dominance. Furthermore, a novel phase waterfall plot method that can identify frequency components with weak amplitudes is proposed to analyze the vibration response characteristics of cracked Jeffcott rotors. Numerical and experimental studies indicate that the phase waterfall plots effectively recognize the weak characteristic frequencies of cracked rotors. This study can also provide references for the crack monitoring of rotor systems.
Jingsong He,Ni Xie,Jianbo Yang,Hong Guan,Weicai Chen,Huisheng Wu,Zishan Yuan,Kun Wang,Guojin Li,Jie Sun,Limin Yu 한국유방암학회 2014 Journal of breast cancer Vol.17 No.3
Purpose: Synuclein-γ (SNCG), which was initially identified asbreast cancer specific gene 1, is highly expressed in advancedbreast cancers, but not in normal or benign breast tissue. Thisstudy aimed to evaluate the effects of SNCG siRNA-treatmenton breast cancer cells and elucidate the associated mechanisms. Methods: Vectors containing SNCG and negative control(NC) siRNAs were transfected into MDA-MB-231 cells; mRNAlevels were determined by real-time polymerase chain reaction. Cell proliferation was evaluated using the MTT assay, cell migrationwas assessed by the Transwell assay, apoptosis and cellcycle analyses were conducted with the flow cytometer, andWestern blot analysis was performed to determine the relativelevels of AKT, ERK, p-AKT, and p-ERK expression. Results:SNCG mRNA levels were significantly reduced in MDA-MB-231cells transfected with SNCG siRNA. Our results indicate that inSNCG siRNA-treated cells, cell migration and proliferation decreasedsignificantly, apoptosis was induced, and the cell cyclewas arrested. Western blot analysis indicated that the proteinlevels of p-AKT and p-ERK were much lower in the SNCG siRNA-treated groups, than in the control and NC groups. Conclusion:SNCG siRNA could decrease the migration and proliferationof breast cancer cells by downregulating the phosphorylationof AKT and ERK.
Jinsong Yang,Jie Liu,Jingsong Xie 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.1
Impact event is the key factor influencing the operational state of the mechanical equipment. Additionally, nonlinear factors existing in the complex mechanical equipment which are currently attracting more and more attention. Therefore, this paper proposes a novel hybrid-separate identification strategy to solve the force identification problem of the nonlinear structure under impact excitation. The ‘hybrid’ means that the identification strategy contains both l1-norm (sparse) and l2-norm regularization methods. The ‘separate’ means that the nonlinear response part only generated by nonlinear force needs to be separated from measured response. First, the state-of-the-art two-step iterative shrinkage/thresholding (TwIST) algorithm and sparse representation with the cubic B-spline function are developed to solve established normalized sparse regularization model to identify the accurate impact force and accurate peak value of the nonlinear force. Then, the identified impact force is substituted into the nonlinear response separation equation to obtain the nonlinear response part. Finally, a reduced transfer equation is established and solved by the classical Tikhonove regularization method to obtain the wave profile (variation trend) of the nonlinear force. Numerical and experimental identification results demonstrate that the novel hybrid-separate strategy can accurately and efficiently obtain the nonlinear force and impact force for the nonlinear structure.
Jinsong Yang,Jianbin Cao,Jingsong Xie,Haixiao Zhao 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.1
A general approach is presented for the free vibration analysis of circular cylindrical shell resting on elastic foundation and subjected to classical boundary conditions of any type. The Winkler/Pasternak model is utilized to simulate the elastic foundation imposed on the cylindrical shell, and then it is easily to derive the potential energy of the elastic foundation. Based on the Flügge shell theory, explicit expressions for the mass and stiffness matrices are obtained. By taking the characteristic beam modal functions as the admissible functions, the Rayleigh-Ritz method is employed to derive the frequency equations of circular cylindrical shell with all the classical boundary conditions and resting on elastic foundation. Once the frequency equation has been determined, the frequencies can be calculated numerically. The excellent accuracy and validity of the present approach are demonstrated by numerical examples and comparisons with the results available in the literature. Finally, some further numerical results are given to illustrate the comprehensive effect of geometric properties and foundation coefficients on the frequencies of circular cylindrical shell in contact with elastic foundation.