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| 1 | Modal characteristics analysis for a flexible rotor with non-smooth constraint due to intermittent rub-impact显示文摘Intermittent rub-impact, during which the contact between rotor and stator is characterized by a ‘‘bouncing' or intermittent type of behavior, is one of the most common rubbing forms in rotating machinery. When the intermittent rub-impact occurs, the non-smooth constraint, which is the phenomenon that the system stiffness changes with respect to the state of contact and noncontact, will appear. The paper aims at discovering the possible effects of the non-smooth constraint on the flexible rotor's modal characteristics by theoretical and experimental methods. The qualitative description for non-smooth constraint is given for the intermittent rub-impact process, and the dynamic modeling for a rotor system with non-smooth constraint is carried out. Meanwhile, the analysis method is developed by Floquet theory and Hill's method to obtain the rotor's modal characteristics. The results reveal that the non-smooth constraint produced by the intermittent rubimpact will increase the modal frequencies and critical speeds of the rotor system significantly.Due to the time-varying features of the constraint stiffness, the modal frequencies for the intermittent rub-impact rotor present fluctuant changes with the increase of rotation speed, which is different from the general linear rotor system. The non-smooth constraint is possible to lead the rotor's instability, and the rotor's instable regions can be expanded significantly for the increase of average constraint stiffness, constraint amplitude and contact time ratio. Non-smooth constraint could also expand the resonance speed and resonance sideband of the rotor system, which sometimes results in amplitude jump phenomenon. | Jie HONG Pingchao YU Dayi ZHANG Zhichao LIANG | 2018 | Chinese Journal of Aeronautics2018，31，3： | 8 |
| 2 | Investigation on nonlinear lateral-torsional coupled vibration of a rotor system with substantial unbalance显示文摘Substantial unbalance may be caused by fan blade off during the operation period of gas turbine engines,and related dynamic problems are very critical to the safety design of rotor system in aero-engine.This article aims to understand lateral-torsional coupled vibration of the rotor system with substantial unbalance.The governing equation of a modified unbalanced rotor system is established based on Lagrangian approach.Then,a mathematical analytical method is proposed in which a linear approximation is derived and the Floquet theory and Hill’s method are incorporated,from which the modal characteristics of the unbalanced rotor are obtained.The modal characteristics of the unbalanced rotor system are revealed comprehensively for the first time.Furthermore,the relation between the modes and responses of the unbalanced rotor is discussed in detail.The results show that the lateral vibration and torsional vibration of the unbalanced rotor are coupled through the inertial terms in the governing equations.Due to the coupling,veering and lock-in phenomena occur between the frequencies of the forward whirl mode and the torsional mode.Furthermore,lock-in can lead to a kind of principal instability.With regard to the response of the unbalanced rotor,both natural vibration components and enforced vibration components appear in the lateral response,while only natural vibration components appear during torsional vibration.Moreover,natural vibration components play a crucial role in the response within the principal instability region and cause divergence of the vibration amplitudes in the lateral and torsional directions. | Jie HONG Pingchao YU Yanhong MA Dayi ZHANG | 2020 | Chinese Journal of Aeronautics2020，33，6： | 8 |
| 3 | Application of complex nonlinear modes to determine dry whip motion in a rubbing rotor system显示文摘Dry whip motion is an instability of rubbing rotor system and may cause catastrophic failures of rotating machinery.Up to now,the related mechanisms of the dry whip is still not well understood.This paper aims to build the relationship between the complex nonlinear modes and the dry whip motion,and propose an effective method to predict the response characteristics and existence boundary of the dry whip through complex nonlinear modes.For the first time,the paper discusses how to use the complex nonlinear modes to predict the dry whip systematically,and as a consequence,the mechanism of the relationship between the complex nonlinear mode and the dry whip is revealed.The results show that the Backward Whirl(BW)mode motion of the rubbing rotor system dominates the response characteristics and the existence boundary of dry whip.The whirl amplitude and whirl frequency of dry whip are equal to the modal amplitude and modal frequency of the BW mode at the jump up point where the modal damping is equal to zero.The existence boundary corresponds to the critical rotation speed where the minimum of the modal damping of the BW mode motion is exactly equal to zero.Moreover,the proposed nonlinear modal method in this article is very effective for the prediction of dry whip of the more complicated practical rotor system,which has been verified by applying the predicted method into a rubbing rotor test rig. | Pingchao YU Yanhong MA Jie HONG Guo CHEN | 2021 | Chinese Journal of Aeronautics2021，34，1： | 4 |
| 4 | Modal analysis strategy and nonlinear dynamic characteristics of complicated aero-engine dual-rotor system with rub-impact显示文摘This paper aims to gain insight into the nonlinear modal characteristics and the possible influence of the modes on the responses for the practical dual-rotor system with rub-impact in aero-engine.The finite solid element method combined with a constraint stiffness model produced by rub-impact is introduced to build the governing equation of the complicated nonlinear dual-rotor system.In order to deal with the efficiency and numerical divergence in the process of solving the nonlinear modes of this large-scale nonlinear system,an analysis strategy is proposed by integrating a two-layer reduction technique into the harmonic balance method.The effectiveness of the analysis strategy is validated by applying to a simple rotor system,which can easily obtain the theoretical result.Based on the modeling method and analysis strategy,the modal characteristics of an aero-engine dual-rotor system with rub-impact are revealed.The results show that the modal frequency of the dual-rotor system increases when rub-impact occurs and has the feature of interval,which allows us to obtain the critical speeds of the rubbing system by traditional Campbell diagram.The rotation direction is an important factor since it can not only affect the gyroscopic effect but also change the friction effect of the rub-impact.It is found that the modal frequencies of the counter-rotation dual-rotor are less than those of co-rotation condition.More importantly,the forward modes of the counter-rotation dual-rotor may be instable when rub-impact occurs at a certain rotor,while the corresponding modes under the co-rotation condition are always stable.Furthermore,by analyzing the rubbing response of the dual-rotor,it is found that the modal characteristics have an important influence on rotor’s response.The instable forward modes existing in the counter-rotation dual-rotor may lead to the divergence of the response when passing the corresponding critical speed. | Pingchao YU Guo CHEN Lunxu LI | 2022 | Chinese Journal of Aeronautics2022，35，1： | 4 |
| 5 | Correction To:Intranasal booster using an Omicron vaccine confers broad mucosal and systemic immunity against SARSCoV-2 variants显示文摘Correction to:Signal Transduction and Targeted Therapy https://doi.org/10.1038/s41392-023-01423-6,published online 17 April 2023 After online publication of the article^(1),the authors noticed two inadvertent mistakes occurred in References that needs to be corrected.The correct text is provided as follows. | Qian Wang Chenchen Yang Li Yin Jing Sun Wei Wang Hengchun Li Zhengyuan Zhang Si Chen Bo Liu Zijian Liu Linjing Shi Xiaolin Liu Suhua Guan Chunhua Wang Linbing Qu Ying Feng Xuefeng Niu Liqiang Feng Jincun Zhao Pingchao Li Ling Chen Nanshan Zhong | 2023 | Signal Transduction and Targeted Therapy2023，8，6： | 1 |
| 6 | Enzymatical hydrolysis of food waste and ethanol production from the hydrolysate显示文摘 | Shoubao Yan Jun Li Xiangsong Chen Jingyong Wu Pingchao Wang Jianfeng Ye Jianming Yao | 2010 | Renewable Energy2010，，4： | 1 |
| 7 | Omicron variants breakthrough infection elicited higher specific memory immunity than third dose booster in healthy vaccinees显示文摘Homologous booster,heterologous booster,and Omicron variants breakthrough infection(OBI)could improve the humoral immunity against Omicron variants.Questions concerning about memory B cells(MBCs)and T cells immunity against Omicron variants,features of long-term immunity,after booster and OBI,needs to be explored.Here,comparative analysis demonstrate antibody and T cell immunity against ancestral strain,Delta and Omicron variants in Omicron breakthrough infected patients(OBIPs)are comparable to that in Ad5-nCoV boosted healthy volunteers(HVs),higher than that in inactivated vaccine(InV)boosted HVs.However,memory B cells(MBCs)immunity against Omicron variants was highest in OBIPs,followed by Ad5-nCoV boosted and InV boosted HVs.OBIPs and Ad5-nCoV boosted HVs have higher classical MBCs and activated MBCs,and lower naïve MBCs and atypical MBCs relative to both vaccine boosted HVs.Collectively,these data indicate Omicron breakthrough infection elicit higher MBCs and T cells against SARS-CoV-2 especially Omicron variants relative to homologous InV booster and heterologous Ad5-nCoV booster. | Pei Yu Zijian Liu Zhuoqi Zhu Jiaqing Yang Min Deng Mingxiao Chen Changchun Lai Weiya Kong Shilong Xiong Li Wan Weikang Mai Lu Chen Yu Lei Shahzad Akbar Khan Jianfeng Ruan An Kang Xuguang Guo Qiang Zhou Wenrui Li Zheng Chen Yuemei Liang Pingchao Li Lei Zhang Tianxing Ji | 2023 | Virologica Sinica2023，38，2： | 0 |
| 8 | Intranasal booster using an Omicron vaccine confers broad mucosal and systemic immunity against SARS-CoV-2 variants显示文摘The highly contagious SARS-CoV-2 Omicron subvariants severely attenuated the effectiveness of currently licensed SARS-CoV-2 vaccines based on ancestral strains administered via intramuscular injection.In this study,we generated a recombinant,replication-incompetent human adenovirus type 5,Ad5-S-Omicron,that expresses Omicron BA.1 spike.Intranasal,but not intramuscular vaccination,elicited spike-specific respiratory mucosal IgA and residential T cell immune responses,in addition to systemic neutralizing antibodies and T cell immune responses against most Omicron subvariants.We tested intranasal Ad5-S-Omicron as a heterologous booster in mice that previously received intramuscular injection of inactivated ancestral vaccine.In addition to inducing serum broadly neutralizing antibodies,there was a significant induction of respiratory mucosal IgA and neutralizing activities against Omicron subvariants BA.1,BA.2,BA.5,BA.2.75,BF.7 as well as pre-Omicron strains Wildtype,Beta,and Delta.Serum and mucosal neutralizing activities against recently emerged XBB,BQ.1,and BQ.1.1 could also be detected but were much lower.Nasal lavage fluids from intranasal vaccination contained multimeric IgA that can bind to at least 10 spike proteins,including Omicron subvariants and pre-Omicron strains,and possessed broadly neutralizing activities.Intranasal vaccination using Ad5-S-Omicron or instillation of intranasal vaccinee’s nasal lavage fluids in mouse nostrils protected mice against Omicron challenge.Taken together,intranasal Ad5-S-Omicron booster on the basis of ancestral vaccines can establish effective mucosal and systemic immunity against Omicron subvariants and multiple SARS-CoV-2 variants.This candidate vaccine warrants further development as a safe,effective,and user-friendly infection and transmission-blocking vaccine. | Qian Wang Chenchen Yang Li Yin Jing Sun Wei Wang Hengchun Li Zhengyuan Zhang Si Chen Bo Liu Zijian Liu Linjing Shi Xiaolin Liu Suhua Guan Chunhua Wang Linbing Qu Ying Feng Xuefeng Niu Liqiang Feng Jincun Zhao Pingchao Li Ling Chen Nanshan Zhong | 2023 | Signal Transduction and Targeted Therapy2023，8，5： | 0 |
| 9 | Modulation of Antiviral Immunity and Therapeutic Efficacy by 25-Hydroxycholesterol in Chronically SIV-Infected, ART-Treated Rhesus Macaques显示文摘Cholesterol-25-hydroxylase(CH25 H)and its enzymatic product 25-hydroxy cholesterol(25 HC)exert broadly antiviral activity including inhibiting HIV-1 infection.However,their antiviral immunity and therapeutic efficacy in a nonhuman primate model are unknown.Here,we report that the regimen of 25 HC combined with antiretroviral therapy(ART),provides profound immunological modulation towards inhibiting viral replication in chronically SIVmac239-infected rhesus macaques(RMs).Compared to the ART alone,this regimen more effectively controlled SIV replication,enhanced SIVspecific cellular immune responses,restored the ratio of CD4/CD8 cells,reversed the hyperactivation state of CD4^(+)T cells,and inhibited the secretion of proinflammatory cytokines by CD4^(^(+))and CD8^(+)T lymphocytes in chronically SIVinfected RMs.Furthermore,the in vivo safety and the preliminary pharmacokinetics of the 25 HC compound were assessed in this RM model.Taken together,these assessments help explain the profound relationship between cholesterol metabolism,immune modulation,and antiviral activities by 25 HC.These results provide insight for developing novel therapeutic drug candidates against HIV-1 infection and other related diseases. | Chunxiu Wu Jin Zhao Ruiting Li Fengling Feng Yizi He Yanjun Li Runhan Huang Guangye Li Heng Yang Genhong Cheng Ling Chen Feng Ma Pingchao Li Caijun Sun | 2021 | Virologica Sinica2021，36，5： | 0 |
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