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Application of coupled analysis methods for prediction of blast-induced dominant vibration frequency 认领 引用 被引量：11
1
作者 Li Haibo Li Xiaofeng +2 位作者 Li Jianchun Xia Xiang Wang Xiaowei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2016年第1期153-162,共10页
Blast-induced dominant vibration frequency （DVF） involves a complex, nonlinear and small sample system considering rock properties, blasting parameters and topography. In this study, a combination of grey relational... Blast-induced dominant vibration frequency （DVF） involves a complex, nonlinear and small sample system considering rock properties, blasting parameters and topography. In this study, a combination of grey relational analysis and dimensional analysis procedures for prediction of dominant vibration frequency are presented. Six factors are selected from extensive effect factor sequences based on grey relational analysis, and then a novel blast-induced dominant vibration frequency prediction is obtained by dimensional analysis. In addition, the prediction is simplified by sensitivity analysis with 195 experimental blast records. Validation is carried out for the proposed formula based on the site test database of the first- period blasting excavation in the Guangdong Lufeng Nuclear Power Plant （GLNPP）. The results show the proposed approach has a higher fitting degree and smaller mean error when compared with traditional predictions. 展开更多
关键词 grey relational analysis dimensional analysis sensitivity analysis dominant vibration frequency prediction
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Effect of vibration frequency on primary phase and properties of grey cast iron fabricated by lost foam casting 认领 引用 被引量：8
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作者 Bo-tao Xiao Zi-tian Fan +2 位作者 Wen-ming Jiang Jun-huai Xiang Xue-fang Yan 《China Foundry》 SCIE CAS 2020年第1期1-7,共7页
The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibra... The properties of gray cast iron(GCI)are affected by density of matrix,size of flake graphite and primary austenite.In this paper,the Y-type specimen of GCI was prepared by lost foam casting(LFC)with and without vibration,and the influence of vibration frequency on the density of matrix,size of primary phase,and properties of the GCI was studied.The results show that the length of the flake graphite and the size of the primary austenite in GCI firstly decrease and then increase with the increase of the vibration frequency.With a vibration frequency of 35 Hz,the length of the flake graphite is the shortest,the primary austenite is the finest and the density of the matrix is the highest.In addition,the tensile strength,elongation and hardness of the GCI firstly increase and then decrease with the increase of the vibration frequency,due to the refinement of the primary phase and the increase of the matrix density.In order to analyze the refinement mechanism of the primary phase of the GCI fabricated by the LFC with vibration,the solidification temperature fields of the GCI fabricated by the LFC with the vibration frequency of 0 and 35 Hz were measured.The results show that the vibration reduces the eutectic point of the GCI and increases the supercooling degree during the eutectic transformation.As a result,the length of the flake graphite and the size of the primary austenite in GCI fabricated by LFC with the vibration frequency of 35 Hz decrease. 展开更多
关键词 vibration frequency lost foam casting grey cast iron flake graphite properties
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Construction and Application of Online Vibration Frequency Response Analysis Method for Converter Transformer Winding 认领 引用
3
作者 Shuyu Wu Fan Zhang Shengchang Ji 《High Voltage》 SCIE EI CSCD 2026年第3期646-655,共10页
The harmonic current and vibration of a converter transformer are effective pieces of information for detecting mechanical faults in the winding.In this paper,the ratio of vibration acceleration to the current squared... The harmonic current and vibration of a converter transformer are effective pieces of information for detecting mechanical faults in the winding.In this paper,the ratio of vibration acceleration to the current squared is defined as the vibration frequency response function(VFRF)of the winding,and then,a novel online vibration frequency response analysis(VFRA)method is constructed.A harmonic load platform is built to simulate the real operating environment of the converter transformer,and it is verified by experimental methods that online VFRA is a simpler and more convenient method for winding mechanical condition detection than offline VFRA.The effects of different factors such as current magnitude and harmonic content on the online VFRA are investigated,and the converter transformer winding mechanical condition is detected by combining the VFRF trace with two numerical indices of Lin's concordance coefficient(LCC)and improved comparative standard deviation(CSD).Laboratory experiments demonstrate that online VFRA has high stability and can effectively diagnose winding looseness faults of different degrees.In contrast to the traditional frequency response analysis(FRA)and short-circuit impedance(SCI)methods,online VFRA has higher sensitivity and detection capability,and is a better method for online monitoring of the winding mechanical condition. 展开更多
关键词 harmonic current online vibration frequency response analysis detecting mechanical faults converter transformer harmonic load platform converter transformerand vibration frequency response analysis vfra method vibration frequency response function vfrf
Natural Vibration Frequency Analysis for a PC Continuous Box-Girder Bridge with Corrugated Steel Web Based on the Dynamic Stiffness Matrix 认领 引用
4
作者 JI Wei LUO Kui MA Wan-liang 《Journal of Highway and Transportation Research and Development(English Edition)》 2020年第1期65-74,共10页
In order to reasonably analyze the influence of shear deformation of corrugated steel web on the natural vibration frequency of PC continuous box girder bridge with corrugated steel webs,first,the element stiffness ma... In order to reasonably analyze the influence of shear deformation of corrugated steel web on the natural vibration frequency of PC continuous box girder bridge with corrugated steel webs,first,the element stiffness matrix of PC box girder bridge with corrugated steel webs is derived by using the energy variation principle.Second,according to the derived element stiffness matrix,the solution program for calculating thenatural frequency of multi-span uniform cross-section PC continuous box girder bridge with corrugated steel webs considering the influence of steel web shearing effect is compiled by MATLAB software.The correctness of the natural vibration frequencies calculated by the MATLA B software is verified by the measured frequency of the constructed bridge and the calculated value by ANSYS 3D FE method.Finally,the influence parameters of the bending vibration frequency of the abovementioned bridge are analyzed.The result shows that(1)The natural frequencies calculated by the proposed program are in good agreement with the measured and FE values of the built bridges.The calculation program has higher precision,the difference of the first 5-order natural frequencies is within 6.01%and 7.32%.(2)The shear defomation effect of corrugated steel webs has great influence on the natural frequency of the subject bridge,while the modification of the shear modulus of corrugated steel webs and the type of corrugated steel webs has little influence on the bending vibration frequency of the bridge,the difference of the first 5-order bending vibration frequencies is within 1.07%and 0.55%,which can be ignored.(3)The dynamic analysis of the subject bridge considering the shear deformation effect can be easily incorporated into the matrix displacement system of the common framed structure,which avoids the complexity of the establishment and solution of the ANSYS FE model,It provides a reference for the calculation and analysis of the bending vibration frequency of the bridge type. 展开更多
关键词 bridge engineering vertical bending vibration frequency dynamic stiffness matrix continuous box girder bridge principle of potential energy stationarity
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Vibration Frequency in Micro-Vibration Therapy in Nursing Care: A Cross-Sectional Study 认领 引用
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作者 Teppei Yamashita Shinsuke Sasaki Mari Azuma 《Open Journal of Nursing》 2023年第4期226-232,共7页
This study investigated the vibration frequency in micro-vibration therapy (MVT) performed as a part of nursing care in Japan. We surveyed 31 nurses (25 women and 6 men) who performed MVT with accelerometers attached ... This study investigated the vibration frequency in micro-vibration therapy (MVT) performed as a part of nursing care in Japan. We surveyed 31 nurses (25 women and 6 men) who performed MVT with accelerometers attached to the backs of their hands, and the data obtained were analyzed. The mean vibration frequency was 8.3 Hz (standard deviation [SD]: 1.9 Hz) bilaterally, with a left-right difference of 0.8 Hz (SD: 1.1 Hz, right > left). Furthermore, vibration frequency was correlated with duration of MVT use (rs = 0.5, P < 0.01). The vibration frequency was higher in men (9.2 Hz, SD: 2.4 Hz) than in women (8.1 Hz, SD: 1.8 Hz), but this difference was not significant (P = 0.34). The vibrations of MVT are of a lower frequency than those of other vibration therapies. 展开更多
关键词 Micro-Vibration Therapy Nursing Care Vibration Frequency
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Dynamic Mechanism and Active Suppression of Rotor Beat Frequency Vibration in a Magnetic Levitation Induction Machine 认领 引用
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作者 Jingxiong He Zhenzhong Su +3 位作者 Qi Liu Dingyang Liu Haoran Zhao Dong Wang 《CES Transactions on Electrical Machines and Systems》 EI CSCD 2026年第2期121-132,共12页
This study focuses on the phenomenon of rotor beat frequency vibration(BFV)in a 2-pole magnetic levitation induction machine(MLIM),systematically investigating its dynamic mechanisms and subsequently applying an estab... This study focuses on the phenomenon of rotor beat frequency vibration(BFV)in a 2-pole magnetic levitation induction machine(MLIM),systematically investigating its dynamic mechanisms and subsequently applying an established method for its suppression.First,the BFV synthesis process is described.Subsequently,three primary disturbance sources in the magnetic bearing(MB)system are identified and analyzed,including rotor unbalance,unbalanced magnetic pull(UMP)and magnetostrictive effect.Through numerical solution of a fourdegree-of-freedom(4-DOF)rotor dynamic model,the theoretical analysis reveals that MLIM-induced BFV consists of three spectral components:(i)rotor rotational frequency(RRF),(ii)electrical fundamental frequency(EFF),and(iii)the sum of EFF and slip frequency(EFF+SF).Building on these findings,we propose the adoption of a well-established notch filtering technique as an effective means to suppress the BFV.The experimental results confirm the correctness of the analysis of the BFV generation mechanism,and in particular of the EFF disturbance mechanism,and also demonstrate the effectiveness of the vibration suppression method. 展开更多
关键词 Active magnetic bearing(MB) 2-Pole magnetic levitation induction machine(MLIM) Beat frequency vibration(BFV) Magnetostriction Vibration suppression
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Frequency and vibration responses of a magneto-rheological sandwich micro-beam based on modified couple stress theory and finite difference method 认领 引用
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作者 M.JAFARI M.MOHAMMADIMEHR 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2026年第7期1581-1602,共22页
In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is ... In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is used to control vibrations.The displacement fields are assumed based on the classical beam theory(CBT)and modified classical beam theories.Based on Hamilton's principle,the governing equations of motion are obtained.To solve these temporal equations,the finite difference method(FDM)with an optimal number of nodes is applied.The effects of various parameters,including viscoelastic properties,magnetic fields,aspect ratio,core-to-face-sheet thickness ratio,MR materials,face sheets,and material length-scale parameters,on the frequency and vibrational response are investigated.In the literature,the effects of different parameters on the frequency response function(FRF)or vibration response are considered.The results obtained from the vibration response and FRF using the FDM show that the viscoelastic property of the MR core causes settling time in the vibration response and a decrease in the excitation frequency of the FRF.Increasing the magnetic field has a negligible effect on the excitation frequency in the FRF,but it increases the vibration response and settling time.The piezoelectric face sheets raise the FRF and suppress the vibration response of the MR sandwich micro-beam compared with the aluminum counterpart. 展开更多
关键词 frequency and vibration responses sandwich micro-beam magnetorheological(MR)core modified couple stress theory(MCST) finite difference method(FDM)
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Long-Term Bridge Health Evaluation Using Resonant Frequency Changes under Random Loading Conditions 认领 引用
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作者 Thi Kim Chi Duong Bich-Ngoc.Mach +2 位作者 Hoa-Cuc.Nguyen Thi Nhu Quynh Trinh Thanh Q.Nguyen 《Structural Durability & Health Monitoring》 EI 2026年第1期86-120,共35页
This study explores theoretical insights and experimental results on monitoring load-carrying capacity degradation in bridge spans through frequency analysis.Experiments were conducted on real bridge structures,includ... This study explores theoretical insights and experimental results on monitoring load-carrying capacity degradation in bridge spans through frequency analysis.Experiments were conducted on real bridge structures,including the Binh Thuan Bridge,focusing on analyzing the power spectral density(PSD)of vibration signals under random traffic loads.Detailed digital models of various bridge spans with different structural designs and construction periods were developed to ensure diversity.The study utilized PSD to analyze the vibration signals from the bridge spans under various loading conditions,identifying the vibration frequencies and the corresponding response regions.The research correlated the observed frequency changes of PSD with the actual deterioration of the bridges over time,identifying patterns that indicate a reduction in stiffness.Experiments demonstrated that frequency changes,particularly in high-frequency regions,are directly related to a reduction in the stiffness of bridge spans.This supports the hypothesis that natural frequencies can serve as effective indicators of structural damage.Furthermore,the emergence and shift of resonant frequency regions provide valuable insights into the extent of damage in actual bridge spans,highlighting the potential for using changes in resonant frequency regions as a new tool for structural damage detection. 展开更多
关键词 Frequency power spectral density vibration signals vibration frequencies resonant frequency regions structural damage detection
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Discrimination of brownheart of Korla pear using vibration frequency spectrum technique 认领 引用 被引量：1
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作者 Xu Hubo Wu Jie +3 位作者 Wang Zhaopeng Gao Yongmao Wang Zhipeng Zhao Zhengqiang 《International Journal of Agricultural and Biological Engineering》 SCIE 2017年第2期259-266,共8页
The purpose of this work was to use a nondestructive method for detecting the brownheart of Korla pear to reduce the chance of infection among pears without brownheart.A mechanical impulse method based on vibration te... The purpose of this work was to use a nondestructive method for detecting the brownheart of Korla pear to reduce the chance of infection among pears without brownheart.A mechanical impulse method based on vibration testing system was used to excite the fruits.The consistent acquisition signal indicated that the test is repeatable at the same positions of fruit equator(cheek).A remarkable frequency signal was excited at 9-12 N force by a rubber tipped hammer.The dominant frequency was identified at the maximum response magnitude to assess the internal defect,and the result was not influenced by the distances between the defect borders and the excitation points.The sharp increase of defect mass could significantly affect the dominant frequency.Relationship between the dominant response frequency(fd)and the defect mass percentage(ω)was characterized by an equation fd=410.649e-0.0833ω+261.947 with a good correlation coefficient(R2=0.925).A defect mass of 2.281%was determined as a discrimination threshold.Once the threshold exceeded 2.281%,the defective pear could be classified with a high accuracy rate of 96.7%.This finding would provide guidance for determining the optimal detecting time to the brownheart of Korla pears,according to the specific storage conditions when the vibration frequency spectrum method is deployed. 展开更多
关键词 nondestructive detection vibration frequency spectrum brownheart of Korla pear internal defect fruit quality
Low frequency vibration tests on a floating slab track in an underground laboratory 认领 引用 被引量：6
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作者 De-yun DING Wei-ning LIU +2 位作者 Ke-fei LI Xiao-jing SUN Wei-feng LIU 《Journal of Zhejiang University-SCIENCE A》 SCIE EI CAS CSCD 2011年第5期345-359,共15页
Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating s... Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures. 展开更多
关键词 Low frequency vibrations Laboratory tests Floating slab track (FST) Vibration isolation efficiency
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Influence of High Frequency Vibration on Deep Drawing Process of AZ31 Sheet at Room Temperature 认领 引用 被引量：12
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作者 温彤 郜瑞 陈霞 《Journal of Shanghai Jiaotong university(Science)》 EI 2012年第4期456-460,共5页
Quasi-ultrasonic vibration with a frequency of 15 kHz and a maximum output of 2 kW was imposed on the deep drawing process of AZ31 magnesium alloy sheet at room temperature,in order to reveal the effect of high freque... Quasi-ultrasonic vibration with a frequency of 15 kHz and a maximum output of 2 kW was imposed on the deep drawing process of AZ31 magnesium alloy sheet at room temperature,in order to reveal the effect of high frequency vibration on deformation behavior of AZ31 during the process.From the drawn results and the observation of the microstructure within the large deformation area,high frequency vibration has a great influence on the formability,the forming load and the failure mode of AZ31 sheet during the deep drawing process;the influence is a comprehensive result of so-called "volume effect" and "surface effect",and relies on the vibrating amplitude.Total forming load decreased significantly as soon as the vibration superimposed.According to the tensile test results of AZ31 bars under ultrasonic vibration,the formability of AZ31 sheet increases firstly with the increase of stimulating energy,then decreases and finally becomes brittle.Under the combined influence of "surface effect" and the "softening" in the "volume effect" near the relative low amplitude of 25%A in the experiment(A is the maximum amplitude),the formability of AZ31 reaches the largest value,and the samples possess the same distribution trend of cracks as those added with lubricating oil.With the increase of excitation energy,the "volume effect" gradually becomes apparent,and finally the "hardening" of the "volume effect" occupies a dominant position. 展开更多
关键词 magnesium alloy high frequency vibration deep drawing formability
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Cascaded quasi-zero stiffness nonlinear low-frequency vibration isolator inspired by human spine 认领 引用 被引量：14
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作者 Guoxin JIN Zhenghao WANG Tianzhi YANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第6期813-824,共12页
Human motion induced vibration has very low frequency,ranging from 2 Hz to 5 Hz.Traditional vibration isolators are not effective in low-frequency regions due to the trade-off between the low natural frequency and the... Human motion induced vibration has very low frequency,ranging from 2 Hz to 5 Hz.Traditional vibration isolators are not effective in low-frequency regions due to the trade-off between the low natural frequency and the high load capacity.In this paper,inspired by the human spine,we propose a novel bionic human spine inspired quasi-zero stiffness(QZS)vibration isolator which consists of a cascaded multi-stage negative stiffness structure.The force and stiffness characteristics are investigated first,the dynamic model is established by Newton’s second law,and the isolation performance is analyzed by the harmonic balance method(HBM).Numerical results show that the bionic isolator can obtain better low-frequency isolation performance by increasing the number of negative structure stages,and reducing the damping values and external force values can obtain better low-frequency isolation performance.In comparison with the linear structure and existing traditional QZS isolator,the bionic spine isolator has better vibration isolation performance in low-frequency regions.It paves the way for the design of bionic ultra-low-frequency isolators and shows potential in many engineering applications. 展开更多
关键词 bionic spine inspired vibration isolator harmonic balance method(HBM) quasi-zero stiffness(QZS) ultra-low frequency vibration isolation
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A high frequency vibration compensation approach for ultrahigh resolution SAR imaging based on sinusoidal frequency modulation Fourier-Bessel transform 认领 引用 被引量：4
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作者 CHEN Siyu WANG Yong CAO Rui 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2023年第4期894-905,共12页
Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results.... Ultrahigh resolution synthetic aperture radar(SAR)imaging for ship targets is significant in SAR imaging,but it suffers from high frequency vibration of the platform,which will induce defocus into SAR imaging results.In this paper,a novel compensation method based on the sinusoidal frequency modulation Fourier-Bessel transform(SFMFBT)is proposed,it can estimate the vibration errors,and the phase shift ambiguity can be avoided via extracting the time frequency ridge consequently.By constructing the corresponding compensation function and combined with the inverse SAR(ISAR)technique,well-focused imaging results can be obtained.The simulation imaging results of ship targets demonstrate the validity of the proposed approach. 展开更多
关键词 synthetic aperture radar(SAR) high frequency vibration compensation sinusoidal frequency modulation FourierBessel transform(SFMFBT)
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Calculations of the vibrational frequency and isotopic shift of UF_6 and U_2 F_6 认领 引用 被引量：2
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作者 张云光 查新未 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第7期262-267,共6页
Molecular structure, vibrational frequency and infrared intensity of UF6 are investigated by using the revised Perdew Burke-Enzerhof function with the triple-zeta polarized basis set. The calculation results are in go... Molecular structure, vibrational frequency and infrared intensity of UF6 are investigated by using the revised Perdew Burke-Enzerhof function with the triple-zeta polarized basis set. The calculation results are in good agreement with the experimental values and indicate the existence of a stable U2F6 molecule with a multiple bonded U2 unit. The calculation results also predict that the D3d symmetry of U2F6 is more stable than D3h. The optimized geometries, vibrational frequencies, and infrared intensities are also reported for U2F6 molecules in D3d symmetry. In addition, the isotopic shift of vibrational frequencies of the two molecules under isotopic substitution of uranium atom are also investigated with the same method. The U2F6 molecule is predicted to be better than UF6 for laser uranic isotope separation. 展开更多
关键词 molecular structure vibrational frequency infrared intensity isotopic shift
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A Highly Sensitive Femtosecond Time-Resolved Sum Frequency Generation Vibrational Spectroscopy System with Simultaneous Measurement of Multiple Polarization Combinations 认领 引用 被引量：2
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作者 谈军军 罗毅 叶树集 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2017年第6期671-677,I0002,共7页
Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identi... Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy （SFG-VS） system. This system is able to measure the spectra with two polarization combinations （ssp and ppp, or psp and ssp） simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations. 展开更多
关键词 Femtosecond time-resolved Sum frequency generation vibrational spectroscopy Ultrafast vibrational dynamics Multiple polarization combination measurement Chiral
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Sum Frequency Generation Vibrational Spectra of Perovskite Nanocrystals at the Single-Nanocrystal and Ensemble Levels 认领 引用 被引量：1
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作者 Renlong Zhu Quanbing Pei +2 位作者 Junjun Tan Xiaoxuan Zheng Shuji Ye 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第5期738-746,I0001-I0003,I0011,共9页
Determination of molecular structures of organicinorganic hybrid perovskite(OIHP)nanocrystals at the single-nanocrystal and ensemble levels is essential to understanding the mechanisms responsible for their size-depen... Determination of molecular structures of organicinorganic hybrid perovskite(OIHP)nanocrystals at the single-nanocrystal and ensemble levels is essential to understanding the mechanisms responsible for their size-dependent optoelectronic properties and the nanocrystal assembling process,but its detection is still a bit challenging.In this study,we demonstrate that femtosecond sum frequency generation(SFG)vibrational spectroscopy can provide a highly sensitive tool for probing the molecular structures of nanocrystals with a size comparable to the Bohr diameter(∼10 nm)at the single-nanocrystal level.The SFG signals are monitored using the spectral features of the phenyl group in(RMBA)PbBr3 and(R-MBA)2PbI4 nanocrystals(MBA:methyl-benzyl-ammonium).It is found that the SFG spectra exhibit a strong resonant peak at 3067±3 cm−1(ν2 mode)and a weak shoulder peak at 3045±4 cm−1(ν7a mode)at the ensemble level,whereas a peak of theν2 mode and a peak at 3025±3 cm−1(ν20b mode)at the single-nanocrystal level.The nanocrystals at the single-nanocrystal level tend to lie down on the surface,but stand up as the ensemble number and the averaged sizes increase.This finding may provide valuable information on the structural origins for size-dependent photo-physical properties and photoluminescence blinking dynamics in nanocrystals. 展开更多
关键词 Perovskite Single nanocrystal Sum frequency generation vibrational spectroscopy Size-dependent property
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Unraveling ethylene carbonate-propylene carbonate disparity at electrode interface using femtosecond sum frequency generation vibrational spectroscopy 认领 引用 被引量：1
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作者 Zhuo Wang Xiaoxuan Zheng +1 位作者 Zijian Ni Shuji Ye 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第6期729-736,I0001-I0007,I0041,共8页
Ethylene carbonate(EC)is an important electrolyte used in lithium-ion batteries due to its excellent electrochemical performance.However,propylene carbonate(PC)differs from EC by only one methyl substituent and exhibi... Ethylene carbonate(EC)is an important electrolyte used in lithium-ion batteries due to its excellent electrochemical performance.However,propylene carbonate(PC)differs from EC by only one methyl substituent and exhibits markedly poorproperties.The EC-PC disparity is still poorly understood at the molecular level.In this study,we demonstrated that femtosecond broadband sum frequency generation vibrational spectroscopy(SFG-VS)with simultaneous measurement of multiple polarization combinations provides a powerful probe for investigating the physicochemical processes at the electrode-electrolyte interface during the charge-discharge cycles of lithium batteries.Using monolayer graphene as the working electrode,we observed the distinct reaction outcomes of EC and PC on the electrode surface.The interfacial reaction of EC occurred only in the first charge-discharge cycle,while the interfacial reaction of PC was ongoing along with the charge-discharge cycles,which explains why EC is a better electrolyte choice than PC.This study provides direct experimental evidence in elucidating the differences in interfacial performance between EC and PC,facilitating a deeper understanding of battery interface reactions and guiding the design of high-performance lithium-ion batteries. 展开更多
关键词 Sum frequency generation vibrational spectroscopy Ethylene carbonate Propylene carbonate Solid electrolyte interphase
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A critical review of wheel/rail high frequency vibration-induced vibration fatigue of railway bogie in China 认领 引用 被引量：3
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作者 Xingwen Wu Zhenxian Zhang +7 位作者 Wubin Cai Ningrui Yang Xuesong Jin Ping Wang Zefeng Wen Maoru Chi Shuling Liang Yunhua Huang 《Railway Sciences》 2024年第2期177-215,共39页
Purpose–This review aims to give a critical view of the wheelail high frequency vibration-induced vibration fatigue in railway bogie.Design/methodology/approach–Vibration fatigue of railway bogie arising from the wh... Purpose–This review aims to give a critical view of the wheelail high frequency vibration-induced vibration fatigue in railway bogie.Design/methodology/approach–Vibration fatigue of railway bogie arising from the wheelail high frequency vibration has become the main concern of railway operators.Previous reviews usually focused on the formation mechanism of wheelail high frequency vibration.This paper thus gives a critical review of the vibration fatigue of railway bogie owing to the short-pitch irregularities-induced high frequency vibration,including a brief introduction of short-pitch irregularities,associated high frequency vibration in railway bogie,typical vibration fatigue failure cases of railway bogie and methodologies used for the assessment of vibration fatigue and research gaps.Findings–The results showed that the resulting excitation frequencies of short-pitch irregularity vary substantially due to different track types and formation mechanisms.The axle box-mounted components are much more vulnerable to vibration fatigue compared with other components.The wheel polygonal wear and rail corrugation-induced high frequency vibration is the main driving force of fatigue failure,and the fatigue crack usually initiates from the defect of the weld seam.Vibration spectrum for attachments of railway bogie defined in the standard underestimates the vibration level arising from the short-pitch irregularities.The current investigations on vibration fatigue mainly focus on the methods to improve the accuracy of fatigue damage assessment,and a systematical design method for vibration fatigue remains a huge gap to improve the survival probability when the rail vehicle is subjected to vibration fatigue.Originality/value–The research can facilitate the development of a new methodology to improve the fatigue life of railway vehicles when subjected to wheelail high frequency vibration. 展开更多
关键词 Wheelail high frequency vibration Vibration fatigue Railway bogie Fatigue damage assessment
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DESIGN AND ANALYSIS OF NOVEL ACTIVE ACTUATOR TO CONTROL LOW FREQUENCY VIBRATIONS OF SHAFT SYSTEM 认领 引用 被引量：1
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作者 YU Yilong LIU Changwen +2 位作者 YANG Yanxiang WANG Shuang ZHANG Junhong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS 2008年第6期41-47,共7页
Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrati... Aiming at providing with high-load capability in active vibration control of large-scale rotor system, a new type of active actuator to simultaneously reduce the dangers of low frequency flexural and torsional vibrations is designed. The actuator employs electro-hydraulic system and can provide a high and circumferential load. To initialize new research, the characteristics of various kinds of active actuators to control rotor shaft vibration are briefly introduced. The purpose of this paper is to introduce the preliminary results via presenting the structure, functions and operating principles, in particular, the working process of the electro-hydraulic system of the new actuator which includes a set of high speed electromagnetic valves and a series of sloping cone-shaped openings, and presenting the transmission relationships among the control parameters from control signals into the valves to active load onto shaft. The course of the work is dynamic, and a series of spatial forces and moments are put on the shaft to get an external resultant force to reduce excitations that induce vibration of shafts. By checking states of vibration, the actuator can control the impulse width and the interval of injection time for applying different control force to a vibration shaft in two circumference directions through the regulating action of a set of combination directional control valves. The results from simulating analysis and experiment show evidence of that this design can satisfy the case of active process of decreasing of flexural and torsional vibrations. 展开更多
关键词 Actuators Low frequency vibration Active control Large-scale rotation shafts System development
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Ordering effects of cholesterol on sphingomyelin monolayers investigated by high-resolution broadband sum-frequency generation vibrational spectroscopy 认领 引用 被引量：1
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作者 Yiyi Li Rongjuan Feng +3 位作者 Lu Lin Minghua Liu Yuan Guo Zhen Zhang 《Chinese Chemical Letters》 SCIE CAS CSCD 2018年第3期357-360,共4页
This report investigated the ordering of the alky chain of sphingomyelin （SMs） monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectr... This report investigated the ordering of the alky chain of sphingomyelin （SMs） monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectroscopy （HR-BB-SFG-VS）. The SFG spectra of the three nature sphingomyelin/cholesterol mixture monolayers with two concentrations of the cholesterol at the air/water interface are performed under different polarization combination. A new resolved CH2 symmetric stretching （d＋, ~2834 cm-1） and the CH3 symmetric stretching （r＋, ~2874 cm-1） mode are applied to characterize the conformational order in the sphingomyelin/cholesterol mixture monolayers. It was found that the cholesterol make the sphingosine backbones more conformational order. During this process, the conformational order of the N-linked acyl chain remains unaltered. Moreover, the sphingosine backbones of SMs have much larger contributions to gauche defects of SMs than one in the N-linked acyl chain. These results presented here not only shed lights on understanding of the interactions of sphingomyelin molecules with cholesterol molecules at interface but also demonstrates the ability of HR-BB-SFG to probe such complicated molecular systems. 展开更多
关键词 Sphingomyelin Cholesterol Ordering effect Air/liquid interface High-resolution broadband sum frequency generation Vibrational spectroscopy
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