Abstract: The damage behavior of hydraulic structure caused by dynamic load attracts more attention at present, and is affected deeply by dynamic properties of the structure. In this work, the testing method of dynamic property of a gravity dam is studied by model test. The ambient vibration testing method was studied mainly and compared with traditional testing method. The experimental results show that ambient vibration testing method can measure the structural dynamic property effectively by structural dynamic response. The mode shape, frequency and damping ratio of model structure is affected lightly by magnitude of ambient excitation. The testing results of dynamic property of model structure are coincident by ambient vibration testing method and traditional testing method. The experimental results also show that ambient vibration testing method can detect the dynamic property of structural damage effectively. The experimental results verify further its effective to structural dynamic property of in suit detection based on ambient vibration.

According to the limitation of traditional envelope spectrum and kurtogram, a novel approach to fault diagnosis of bearing based on dual-tree complex wavelet packet transform and kurtogram is presented. The dual-tree complex wavelet packet transform is substituted for the filter in spectral kurtosis. The shortcomings of traditional kurtogram based on the FIR and short time Fourier transform filters is overcome and its accuracy in detecting transients in a signal from strong background noise is improved. Firstly, the bearing fault vibration signals were decomposed into various frequency band signals. Then the spectral kurtosis was computed and the maximum kurtosis was found. In the end, the filtered signal that maximizes kurtosis and its envelope spectrum were obtained. Therefore, the characteristics of the bearing faults can be recognized according to the envelope spectrum. The experimental results show that not only the frequency band selection accuracy and signal noise ratio are improved, but also the faults of the bearing can be effectively detected.

For a complex sinusoid model (CSM), there exists a set of explicit expressions for spectrum correction. However, it is not clear whether there exist corresponding formulas for double-frequency model (DFM). To determine feasibility of the explicit expressions to the DFM, the innate of ratio correction for CSM was analyzed. The explicit correction formulas were present for the DFM without windowing, and were examined by a DFM signal with one strong component amplitude 10 times the weaker one. The study shows, firstly, the essence of existence of simple correction expression for the CSM is that the spectrum functions of common windows can be factorized as transcendental part multiplying a rational fraction, and absolutes of the former are equal on the neighbor lines of discrete spectrum. Secondly, with the above properties, the frequency equations for DFM, only containing the rational fraction, can be deduced. Only for the case of the DFM without windowing, can the frequency equations be simplified to a quadratic polynomial, and will be implicated with at least cubic polynomial for other cases, such as Hanning window. In conclusion, it is not worthy or impossible to find the explicit correction expressions except for the DFM without windowing. The simulation results show that, the precision of the given correction expression can be achieved for the strong component better than the weaker one. In the frequency scanning 0.5~2.0 resolutions of the fast Fourier transform. But the CSM based correction is preferred if the frequency difference of DFM is greater than 2 canonical resolutions of FFT.

This paper presents a method which added pontoon to each tendon in order to improve the motion response of TLP in extreme marine environment. The analysis model of the TLP with additional pontoons which has coupled motion response is built. And this model is solved by iterative method which is presented in this paper. The hydrodynamic parameters of hull and additional pontoons are calculated first, then the coupled dynamic response among the hull, additional pontoons and tendons under the wind, wave and current loads is analyzed according to the diffraction/radiation wave theory, considering different size and position of pontoon and using AQWA12.0 which is famous fluid dynamics analysis software. The results show that: the surge and heave of TLP are caused mainly by wind and current loads, and the pitch of TLP is caused mainly by wave loads; the additional pontoons can significantly reduce the motion response of TLP which is affected by size and position of additional pontoons, but additional pontoons have little influence on the wave frequency motion response of TLP.

The frame structure with multi-grid composite walls is a dual seismic structure. The deformation feature of the structure is different from common frame or shear wall, and the natural vibration period of the structure can not be calculated with the method for the frame-shear wall structure. Based on the theory of Timoshenko dual variable beam and collaborative work model, the frequency equation for the structure is derived, and the natural period calculation formula is established combined with the boundary conditions of structure. The approximate calculation method for the basic formula is gived simultaneously. Example analysis shows that: the natural vibration period of the structure can be impacted by the shear stiffness of the lightweight composite wallboard significantly, especially to the high order mode. The influence of the shear deformations of the composite wall to the natural vibration period of the high order mode can not be ignored. The error of approximate calculation method by the basic formula is not large comparing with the analytical solution, and can meet the engineering calculation accuracy requirements.

The nonlinear blind source separation algorithm based on kernel function has been widely applied in blind signal progress. However the learning rate of traditional kernel function method is fixed. If the learning rate is unsuitable, the aogorithm would be convergenting difficult or would never convergent. So combined with simulated anneling aogoruth ,an adaptive nonlinear blind source separation based on kernel function was proposed. The result of simulation and experiment indicate that the improved algorithm can improve the convergence performance and the effect of BSS. The improved algorithm has better ability of noise reduction and feature extraction than fixed rate nonlinear blind source separation.

This paper proposes the fault detection and isolation (FDI) technique and presents the design method of FDI filter in active control system of structure based on H∞ robust control theory. The FDI system model is constructed according to H∞ object which changes the fault detection problem to a robust control problem. The H∞ optimal controller named FDI filter is worked out by linear matrix inequality (LMI). Simulation results for a three-story building demonstrated the effectiveness of FDI filter. This paper can provide a reference for the structure health monitoring of active control system and is the base of the fault tolerant control.

In order to obtain cushion characteristic regularity to change each parameters, Based on dynamic equations, thermodynamics equations and flow equation of venting orifice, an analytical model has been built up and validated by Hyperworks. Then, based on the model, the deceleration characteristic was investigated. A series of simulations were conducted to find out the influence of cushioning characteristics, such as volume ratio of slaver-master, initial pressure and venting orifice area. The initial inflation pressure also is a key parameter to affect the cushioning properties, and the maximum deceleration decreases with increase in initial inflation pressure, but at the same time the ending velocity of the heavy equipment will have a tiny increase; If the venting orifice area is too small, the airbag will rebound because the impact energy can’t be released in time; but if the venting orifice is too large, the ending velocity of the heavy equipment will exceed the limitation because no enough impact energy is transferred to the airbag attenuation system.

Equipment performance degradation assessment is the complete development of existing fault diagnosis techniques. It can give effective reference to the intelligent proactive maintenance to realize near-zero downtime. Carrying out the research of performance degradation assessment, we can realize the predictive maintenance for the equipment which can improve the reliability of the equipment. Kolmogorov-Smirnov test based on AR model is proposed by this paper. According to the analysis of data from rolling bearing’s whole life time (normal-fault-failure), the proposed method can effectively realize the performance degradation assessment and prognosis to the bearings. Compared with traditional method, it can not only obviously detect incipient weak defect and indicate performance degradation process but also detect abnormal stage earlier before the bearing steps into failure in some conditions. This point is significant in condition maintenance and prognosis.

ARJ aircraft landing gear noise spectra and contours were obtained from fly-over measurements.In order to di-stinguish between landing gear and other noise sources array signal processing technology was used, the result shows:A- RJ aircraft landing gear noise is broadband with some single tones,which energy is mainly in 900Hz below.The possible noise sources were analyzed, and hence supporting landing gear noise reducing design.

A dynamics model of bending-tensional-axial-swing for two-stage helical gear transmission is developed, in which time-varying gear meshing stiffness, error and backlash are considered. The dynamic equation of the helical gear transmission is calculated and the dynamic response is gotten. The dynamic finite element model of gear case is established. The dynamic response of gearcase is calculated based on identification of the dynamic parameters of bearing combination. For the establishment of dynamic model of the whole gear system including two subsystems that are gear transmission and the box, the dynamic analysis of whole gear transmission system is realized.

Due to the influence by human factors on the stochastic subspace identification results, hierarchical clustering algorithm is introduced to overcome this shortcoming. spurious modes resulting from noise or model redundancy can be removed according their mode energy or mode similar index which describes the similarity between modes obtained by two different algorithm; the hierarchical clustering method is introduced to pick up the system modes, the results can be classified into several categories according the similarity between the results which can be calculated by eigenfrequencies, damping ratios, mode shapes and mode energy, some categories will be selected if the number of its elements is large enough. A numerical example and an experimental example are presented to demonstrate the efficacy of the method.

Motor is one of the main sources of vibration and internal and external noise in the electric vehicles（EV）. Therefore, designers are expected to can predict vibration and noise performance in the design stage of motor. Based on the finite element analysis of electromagnetic field theory, the radial force wave of permanent magnet brushless dc motor used in vehicle is studied by simulation and calculation；Then a dynamics model of motor stator is discussed by stimulation, which achieves the goals to analysis the vibration of motor stator. The simulation results are proved by motor vibration experiment results, which verify the correctness of the analysis and lay a foundation for optimization design of the low noise motor in the future.

Three-dimensional Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are performed to investigate aerodynamic forces on a circular cylinder in linear shear at Reynolds numbers of Re=60-1000. The shear parameter , which is based on the velocity gradient, cylinder diameter and upstream mean velocity at the center plane of the cylinder, varies from 0 to 0.30. The movement of the stagnation point and separation points, and lift coefficients with shear parameter are studied. The results show that the stagnation point moves to the high-velocity side almost linearly with shear parameter, and this result mainly influences the aerodynamic forces acting on a circular cylinder in shear flow. Both the Reynolds number and shear parameter influence the movement of the stagnation point and separation point. The lift force increases with increasing shear parameter and acts from the high-velocity side to the low-velocity side.

A dynamic elastic-plastic microplane constitutive model for concrete based on M2 is presented in this paper. The state of each microplane ischaracterized by normal deviatoric and volumetric strains and shear strain.
The strain-stress relations for deviatoric and shear component is described as elastic-plastic model. A new concept: failure strain is achieved. If strain component on microplane exceed failure strain, the stress will be zero. The parameter determination method and analysis is introduced. In the end, three types of test data for concrete from literatures are fit by the model presented in this paper and the results are good which shows the model are reasonable and accurate.

Settlement will occur at subgrade of high-speed railroad caused by repeated loadings from train traffic. Train’s operation speed has a direct correlation with the settlement of railroad subgrade. As train’s running speed increases, the criteria for controlling differential settlement of railroad subgrade becomes higher. Meanwhile, the further increase of train velocity is limited by the subgrade’s differential settlement. It is therefore necessary to investigate the influence of subgrade settlement on the vibration of train and track structure. An updated numerical model is developed based on traditional vertical train-track coupling theory, in which the CA mortar and concrete base beneath slab track are both taken into account. The calculated and in-situ tested results are compared to validate the model and the computation program. Using the program, the amplifications of train-track interaction under different conditions of roadbed settlement and train velocities were analysed. It is concluded that while short-range roadbed settlement result in higher axle acceleration, car body vibration does not increase obviously due to the high frequency of vibration. Therefore, amplitude of settlement should be controlled under the safety standard (axle load reduction rate). In the case of long-range roadbed settlement, however, car body vibration increases obviously. Amplitude of settlement should therefore be controlled under the comfort standard (car body acceleration). The specific control parameters are given at the end.

The nonlinear aeroelastic phenomena of a two-dimensional panel is studied in detail. Von Karman’s large deformation plate theory is used to describe the panel deformation, and the aerodynamic loads can be obtained from the first order piston theory. Thus the nonlinear partial differential equation of the system is derived. Then, the nonlinear Galerkin method based upon Inertial Manifolds with Delay (IMD) is applied to the approaching of the governing equations. By this method, the higher-order modes are expressed by the lower-order modes and a time delay is introduced. Thus the same precision is kept and large computation time is saved. Finally, the numerical examples are given, and the dimensionless dynamic pressure and the dimensionless compressive internal force are considered as bifurcation parameters, respectively, to study the stability and bifurcation of the response. In particular, the route to chaos by intermittent transition is studied, and the periodic windows and self-similarity phenomena are captured in the chaos region. Through the phase portraits, FFT analysis and Lyapunov exponent, it demonstrates that there exist four distinct regions, namely, stable, buckling, synchronous and non-synchronous motions in the system. In the non-synchronous region, a rich variety of nonlinear responses, such as double-period motion, quasi-period motion and chaotic motion, are found. The results can gain a fundamental understanding and developing of the nonlinear phenomena.

Aiming to the characteristics of real passive sonar signal that broad-band, nonstationary and little knowledge of statistics. A fusion cost function is established which combined with the property of time delay structure and non-Parametric under broad-band convolution mixing model. Using a non-parametric kernel density estimation technique, the algorithm performs simultaneously the estimation of the unknown probability density functions of the source signals and the estimation of the unmixing matrix. The proposed algorithm uses the optimized unmixing matrix and estimated target source signals to achieve a bearing-energy spectrum in each frequency bin which accumulated to obtain the broad-band bearing-energy spectrum. Broad-band simulation results and real sea trial shows that the proposed method is close to the minimum variance distortionless response (MVDR) and multiple signal classification (MUSIC) methods in the aspect of bearing resolution and estimated accuracy, however, which play better in the aspect of weak target detection in which strong interference exists.

To improve the control performance of passive adjustable frequency Tuned Liquid Column Dampers (TLCD), Semi-active Variable Stiffness Tuned Liquid Column Damper (SAVS-TLCD) is presented in this paper, with the online adjustable stiffness of additional springs. The state of additional stiffness can be ON or OFF according to the requirements of the control system during the vibration process. The stiffness of the vibration control system includes two parts, on of which is provided by the restore force of liquid motion and another one of which is provided by the spring of the variable stiffness device. The equation of motion of the SAVS-TLCD is derived by the Lagrange equation. The influence of variable stiffness on the control performance is numerical analyzed through a single degree of freedom structure. The frequency widths of reduction are compared for passive TLCD, semi-active variable damping TLCD and semi-active variable stiffness TLCD with different frequency ratios of external load to the structure. The control performance of SAVS-TLCD is also studied on the condition that there is a little error between the frequency of TLCD and the structure. The control performance of SAVS-TLCD to multiple degree of freedom system is verified by a five-story structure subjected to harmonic and earthquake excitations. The results indicate that SAVS-TLCD has larger frequency width of reduction and can still be effectiveness though there is a little error between the frequency of TLCD and the structure.

The new non-consolidation of isolated structure proposed for low-rise and multi-storey buildings structure and the non-consolidation bearing were conducted in the paper. The static tests of viscoelastic material and the non-consolidation bearing were performed in order to study mechanical properties of viscoelastic material and the non-consolidation bearing. Experimental results show that the two viscoelastic material have similar energy dissipation capacity, and the vertical stiffness is great and the vertical energy dissipation capacity is limited of the bearings. Experimental results also show the bearing the horizontal hysteresis curve is a double cone, and the equivalent damping ratio is 15% to 35% at different parameters.

A power plant mount system with controllable damping characteristics in a broader frequency range is very important for active isolation. The operation principle and damping characteristics of a magneto-rheological (MR) semi-active mount in squeeze mode are analyzed. A vertical vibration isolation model of a power plant is proposed. A fuzzy adaptive control (FAC) system utilizing a scale factor self-turning algorithm is designed to decrease the vertical excitation force of the power plant in different operation states. A revised skyhook control strategy is also adopted to dissipating the energy by restraining the vibration of the power plant. An experimental isolation system of one real power plant is presented. The isolation test in different conditions is carried out. Experimental results show that the MR mount system can decrease the absolute force transmissibility ratio to 25%, which is better than that of rubber mounts at lower rotating speed. Test confirms that FAC，which considers vibration transmissibility and excitation frequency, can provide better performance in reducing the total vertical transmitted force than skyhook controller, which is used on vibration isolation by restraining the vibration energy of the power plant .

The international standard ISO 6954, prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock, has experienced two versions: ISO 6954-1984, which gives the guidelines for the overall evaluation of vibration in merchant ships, and ISO 6954-2000, which gives guidelines for the measurement, reporting and evaluation of vibration with regard to habitability on passenger and merchant ships. There are significant differences between the two versions, although the two criteria are both applied now. The main purpose of this paper is to compare the current version with its predecessor, mainly for theoretical approach and practical measurement. Comparison between two versions by some key classification societies and relevant technical papers is introduced as well. The goal is to give some preliminary discussion about the application of the ISO 6954 code.