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18 December 2010, Volume 30 Issue 6 Previous Issue    Next Issue
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2.振动理论与数值解法
3.运载工具振动与噪声
5.建筑振动与建筑声学
6.信号处理与故障诊断
8.标准规范与评价
6.信号处理与故障诊断
7.减振降噪设备和器材
9.振动噪声测试技术
10.工程实践


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2.振动理论与数值解法

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The Flutter Study of Supersonic Wing-Body Combination QUAN Wei-zhuo;FANG Ming-xia 2010, 30(6): 1-4.  Abstract ( )   Aircrafts’ flutter is the self-excited vibration phenomenon occurred in structures with the high-speed airflow, especially for the supersonic and hypersonic aircraft. Because of the Complexity of modern aircrafts, there will be great difference between the traditional flutter analysis and actual situation. In this paper, the dynamics substructure method which is particularly suitable for modeling complex structures is used to build the wing-body combination flutter equations in consideration of the supersonic flow and its structure characteristics. By dividing the entire structure into fuselage and wing substructures, vehicle’s aerodynamic distribution will be calculated based on the nonlinear aerodynamic theory and finite element software. Aircraft’s modal and flutter characteristics will be gotten in order to get vehicle’s vibration and flutter data under established working conditions. In order to enhance the credibility of the calculation, the result will be compared with the traditional wing-body vehicle flutter result. Finally, theoretical analysis methods by dynamic substructure method will be assumed for the supersonic vehicle flutter analysis, providing new theoretical and calculation methods for supersonic aircraft flutter analysis. Related Articles | Metrics

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Model and calculation method for lateral regenerative chatter of circular saws ZHANG Jia-e;DUAN Guo-lin;YAO Tao;CAI Jin 2010, 30(6): 5-8.  Abstract ( )   The lateral regenerative cutting force can be found through analyzing the lateral vibration of circular saws in working condition. So the governing equation for lateral regenerative chatter is obtained based on the Kirchhoff plate theoretical. Applying the Galerkin procedure leads to a delay differential equations which contain each order of unknown mode shape component. A MTLAB program which describe the lateral regenerative chatter of circular saws is compiled through expressing the delay differential equations as state variables. Each order of mode shape component can be solved by call the DDE function. So the lateral regenerative chatter of circular saws can be calculated. Related Articles | Metrics

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Coupled Vibration Analysis of Three Principle Trusses Arch Bridge and Vehicles 2010, 30(6): 9-12.  Abstract ( )   According to the theory of train-bridge time dependent system, the finite element models for the dynamic analysis of train and bridge are established respectively. By computer simulation, it studies the spatial vibration response of coupled system when trains run through the three principle trusses arch bridge at different speeds. The results provide a reference for design. Related Articles | Metrics

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Stability Analysis of Active Framed Structure 2010, 30(6): 13-17.  Abstract ( )   This paper is concerned with stability analysis of active framed structure by means of pole-zeroes and root loci. The results from theoretical derivation and numerical simulation show that the open-loop pole-zeroes of active framed structure with collocated actuator and sensor pairs take on the property of spaced arrangement, and the closed-loop root loci are located in the left-half complex plane regardless of changes in control gain. So the active framed structure with collocated actuator and sensor pairs is asymptotically stable, also the stability does not change with changes in structural parameters, in other words, which is robust with regard to structural parameters. Related Articles | Metrics

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Analytic Study for the Free Vibration of Systems with 2010, 30(6): 18-22.  Abstract ( )   A polynomial fitting method was proposed to express the elastic force of general smooth nonlinear conservative autonomous equation as the sum of infinite series approximately, which is the requirement of the multigrid method, and thus to get the general formula of analytical solutions of the conservative system by solving the modified nonlinear equation with the multigrid method. Comparison between the approximate analytical solution and the numerical solution shows that the multigrid method has a higher accuracy when the polynomial is better fitted. Related Articles | Metrics

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Research of Active Vibration Control of the Structure Based Giant Magnetostrictive Actuator 2010, 30(6): 23-26.  Abstract ( )   In this paper, the mechanism of expansion，the characteristics of magnetostrictive and the coupling characteristics of the Giant Magnetostrictive Material(GMM) were introduced firstly. Based on the characteristics of GMM and the requirements in industrial application, we designed a new Giant Magnetostrictive Actuator (GMA). Finally, a method for active vibration control has been investigated in the field of high precision vibration control. The results of an example illustrate that this intelligent control device can reduce the structural responses induced by the earthquake efficiently. Related Articles | Metrics

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A study of vibratory stress relief based on stress work equivalence method HU Yong-Hui;Yun-xin WU;Jun-kang GUO 2010, 30(6): 27-33.  Abstract ( )   Residual stress relief (VSR) is used to release residual stresses in components, which is a kind of stress relaxation phenomenon occurring at constant strain range with the peak stress decreasing with cycle. VSR causes stress relief and local plastic deformation in stress concentration regions. Based on equivalent linear elastic model, stress work equivalence method could be used to calculate local stress and strain range of power-law hardening materials like 7075 high strength aluminum alloy in order to obtain important data which may be difficult measured by experiments. Based on the similarities between the calculated stress-strain curve and that observed by other researchers from experiments or finite element analysis, applications of stress work equivalence method in VSR analysis could be instructive and meaningful to experiments and engineering practices. Related Articles | Metrics

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Optimal Design of Hydraulic Stewart Platform Based on Resonance Frequency 2010, 30(6): 34-38.  Abstract ( )   The legs of Hydraulic Stewart platform were considered as virtual single open-loops. Local reference frames(LRFs) of manipulator components were established according to the mechanism configurations. RPY angular description was used in transfer matrix to transform components stiffness matrix from LRFs to the fixed reference frame(FRF) and resonance frequency equation was obtained. Optimal model based on mechanism workspace, cylinder stoke etc was established to synthetically consider resonance frequency of the Stewart platform. Quasi-Newton algebra(QNA) and Genetic algebra(GA) were applied respectively to maximize the minimum resonance frequency of the system. Simulation results show that the minimum resonance frequency and workspace are contradictory factors and should be considered synthetically in design. Related Articles | Metrics

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Vibration reduction technologies research of main propulsion power with one gear case Gong Li-Qin;LiFeng Yao 2010, 30(6): 39-42.  Abstract ( )   The gear case in existing and local warship at home is usually all rigid fixed on a base at the ship body , only a few gear case of ship adopts hard flexibility conjunction of method, the vibration reduction level is not well. The gear case’s structure noise which spread to a ship body become influencing the warship ship radiation noise, a voice of main noise. In this article, via designing and testing the gear case raft installation, we study the gear case’s vibration. The test results indicate that the vibration reduction level of the gear case raft installation is above 25dB. Related Articles | Metrics

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Numerical Calculation on Fluid-structure Coupling Vibration of Water-conveying Pipe 2010, 30(6): 43-46.  Abstract ( )   Numerical calculation on fluid-structure coupling vibration responses of a water-conveying pipe was carried out by the method of characteristics (MOC), and four-function model was adopted in the calculation. Researches about the influence of wave speed adopted in pipe-dividing on numerical calculation results and the influence of pipe structure-damping on vibration responses of water-conveying pipe were completed, the numerical results showed that the least wave speed (liquid pressure wave speed for four-function model) should be adopted to divide pipes to get fluid-structure coupling vibration responses of fluid-conveying pipe by MOC, and pipe structure-damping has more obvious effect on the vibration responses of the water-conveying pipe than friction between pipe and liquid, and the pipe structure-damping decays the vibration of the system fast. Related Articles | Metrics

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Characteristic Analysis of Multidimensional Coupling Vibration for Floating Raft Isolation System ZHAO Fei 2010, 30(6): 47-50.  Abstract ( )   A 3D dynamics model of floating raft isolation system is established. This system comprises multi-source excitation, upper isolators, rifid floating raft, lower isolators and elastic foundation. The effect of multi-dimension wave propagation is considered, and the dynamic transmisson equations and power flow expressions are provided utilizing the substructure mobility method. Results of numerical simulation show that multiple resonance peaks are excited in the low frequency domain, and the power flow is increased due to the flexural resonance modals of the elastic foundation and the standing wave effect of the isolators in the high frequency domain. Reducing the isolator stiffness can significantly decrease the power flow but also makes the standing wave effect be advanced. Power flow transmitted to the foundation can be reduced by increasing the raft mass. Related Articles | Metrics

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A Method for Computing Static Stiffness of Complex Structural Rubber Isolators Wang Xiao-Li 2010, 30(6): 51-54.  Abstract ( )   It is difficult to find analytical formulas to compute static stiffness of rubber isolators with complex shape and irregular sections. Combined rubber isolator’s manufacturing, Orthogonal Design and the learning algorithm of Neural Network, a non-linear global mapping function is established for the relation between the rubber isolators’ geometric parameters and their stiffness in x,y and z directions. It will give an estimation to rubber isolators’ stiffness instead of finite element method. The computing results show that the neural network established for estimating the stiffness of rubber isolators is feasible. Related Articles | Metrics

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Shock Experiments Research of Elastomer Damper and Modeling Analysis WANG Gan-Cheng 2010, 30(6): 55-57.  Abstract ( )   By the method of combining both of the experiments and theories, this work studies the elastomer damper with solid-liquid coupling and conducts the shock experiments to analyze the shock characteristics of the damper with solid-liquid coupling. Meanwhile, a dynamics model is established for the shock experiments and parameter is identified in this work. The research has theoretically significant guidance and reference to research on the shock characteristics of the elastomer dampers and dynamics modeling. Related Articles | Metrics

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Modeling the Vibration Isolation System With Flexible Plate Based on the Theory of Flexible Multibody Dynamics 2010, 30(6): 58-62.  Abstract ( )   The vibration isolation system onboard ship differs from other isolation systems in its base flexibility. The dynamic equation of the flexible base plate is formulated using Rayleigh-Ritz method. By applying flexible multibody dynamics, the dynamic model of onboard vibration isolation system is derived. Related Articles | Metrics

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Free Modal Analysis of Crankshaft of 4-Cylinder Diesel Engine 2010, 30(6): 63-66.  Abstract ( )   The 3D model of a four-cylinder crankshaft was established with CATIA software, and then a free modal analysis of the crankshaft was carried out with ANSYS. Through the analysis, the inherent frequencies and mode shape of first 8 order modes were obtained respectively. The free modes of the crankshaft verified by testing. Comparison shows the results of FEA estimation are in good agreement with those of testing and the rusult of FEA is creditablility. It is a perfect base of forced vibration analysis and structure optimum desigin for crankshaft. Related Articles | Metrics

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optimization design and mode experimentation of Fixture for vibrancy test 2010, 30(6): 67-69.  Abstract ( )   This paper introduces optimization design to the fixture design process to raise efficiency and quality. The fixture after machining were experimented and then the reliability and applicability were testified through verifying the result of mode analysis. Therefore, this paper provides a suit of scientific design theory and verification method for fixture design. Related Articles | Metrics

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Experimental Study of Powertrain Rigid Modes Based on Operational Modal Analysis Method 2010, 30(6): 70-74.  Abstract ( )   Two kinds of powertrain mounting system (PMS) rigid modes identification methods based on operational modal analysis (OMA) are presented. These methods include frequency domain decomposition (FDD) and stochastic subspace identification (SSI). The FDD and SSI methods are used to extract the modal parameters separately. At idle condition the bounce and pitch modes of PMS can be identified using FDD and SSI method, and the powertrain’s harmonic modes are also detected. While all the six rigid modes of PMS are identified using FDD and SSI method at white noise excitation. The consistency and accuracy of extracted modal parameters were discussed by comparing the results with OMA and EMA methods. The results are accurate and reliable that can be used for PMS rigid modes identification and dynamic modification. Related Articles | Metrics

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Exact Synthesis of Structural Random Responses Using Substructure Modes YING Zu-Guang;Wei ZHANG 2010, 30(6): 75-78.  Abstract ( )   Related Articles | Metrics

3.运载工具振动与噪声

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A Research on the Weight-reduction of Car-body Based on Stiffness and Model Sensitivity Analysis 2010, 30(6): 79-82.  Abstract ( )   A FEM model for a car is built. On the basis of body stiffness and modal analysis, the optimization design variables are determined through stiffness and modal sensitivity analysis. Then an optimization on the thickness of body panels is conducted with an objective of minimizing the mass of body structure and a constraint of meeting the requirements of stiffness and modal. Related Articles | Metrics

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Topology Optimization Design for a Powertrain Mount Framework HU Pei-Long 2010, 30(6): 83-86.  Abstract ( )   Taking a framework of a commercial vehicle powertrain mount for example, this paper establishes the mathematical model of topology optimization base on the variable density method and its solution. An optimization design for the mount framework which under single load case is carried out by using Optistruct model of Hyperworks. The mount framework is redesigned based on the results of optimization and the production experience. The stress, deformation and volume of the mount assembly are calculated by using the ABAQUS. The results demonstrate that the optimized mount framework is safer and lighter. Related Articles | Metrics

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Co-simulation analysis of Automotive Semi-active Suspension 2010, 30(6): 87-90.  Abstract ( )   Using a new multibody simulation software SIMPACK as platform, a whole CHANGHE mini-car model was built. A fuzzy controller was adopted to control the full car model. Random input running test and pulse input running test simulation were carried out under co-simulation of SIMAT. The results show that, compared to passive suspension, the full car model with fuzzy control can reduce vibration effectively, and improve automotive ride comfort. Related Articles | Metrics

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Idle Abnormal Interior Noise Source Identification Based on Psychoacoustic Analysis and Sound Intensity Measurement Duan Xiao-Cheng;De-lin YOU;Bao-jun SHEN;Xing HUANG 2010, 30(6): 91-95.  Abstract ( )   For an idle interior abnormal noise during vehicle prototype phase, sound quality evaluation was implemented based on psychoacoustic analysis approach, which indicated the subjective difference between normal noise and abnormal noise in quantitative objectively to some extent. The main idle abnormal noise source spectrum range was initially identified from 200Hz to 400Hz using spectral analysis method. The acquisition abnormal noise data were filtered in range of 200Hz to 400Hz, and the filtered noise playback was compared with normal noise, which further verified the idle abnormal noise frequency range previously described. The engine compartment sound field distribution was obtained using sound intensity measurement. The analysis results rapidly and accurately showed that the engine timing pulley system was the main source which caused idle abnormal noise. The idle abnormal noise can be effectively eliminated by controlling engine mount dynamic stiffness. Related Articles | Metrics

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The development and application of noise and vibration analysis system for motor vehicle parts TAN Xi;Da-wei DONG;Bing YAN;Chuan ZHANG 2010, 30(6): 96-100.  Abstract ( )   A noise and vibration analysis system for motor vehicle parts is developed from both hardware and software design. The system takes time-domain analysis, spectrum analysis and order analysis as signal processing core, and can be effectively used in analyzing stationary signal and run-up and run-down non-stationary signal. The application of the system is introduced briefly by an example of noise and vibration testing for some type of alternator in run-up overload condition. Experiments were carried out for various motor vehicle parts in the last two years, and the results show that the system is correct and reliable, and has practical engineering value. Related Articles | Metrics

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Aerodynamic Noise Outside High-speed Vehicle by Numerical Simulation and analys 2010, 30(6): 101-104.  Abstract ( )   Numerical simulation and analysis of distant field noise around model was conducted using large eddy simulation and FW-H acoustics equation of soft ware Fluent. It is obtained that the frequency characteristic and velocity characteristic of the aerodynamic noise outside high-speed vehicle ,and it is found that the side scuttle of the vehicle has the biggest influence to the distant field noise.Finally it is found that the distant field noise is small when the side scuttle and the horizontal plane included centain angle through analyzes to the side scuttle.The result shows that the analogue result by CFD numerical simulation method coincides with the test result. It can be concluded that the calculations are available for project but the precision of simulation need be improved. Related Articles | Metrics

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Simulation and Experimental Analysis of Vibration Characteristic of Rearview Mirror 2010, 30(6): 105-108.  Abstract ( )   To make a test to one type of rearview mirrors, it is easy to find that the first nature frequency exists below 80Hz, and the vibration exceeded the standard. In order to reach the standard, some simulations and experimental analysis of those rearview mirrors were made. Various structural parameters which relates to structural nature frequency and vibration amplitude was analyzed. Given some effective methods which can decline the amplitude, and the results was so better that reached the test standards exactly Related Articles | Metrics

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Analysis of the Effects of Signal Control on Traffic Noise LI Feng 2010, 30(6): 109-113.  Abstract ( )   The single vehicle noise emission levels and acceleration adjustments for three types of vehicles at a reference distance are determined by measurement. Then by combining microscopic traffic flow simulation, vehicle noise emission levels and the noise propagation model, the dynamic traffic noise under the continuum traffic flow in signal control and the interrupted traffic flow without signal control are respectively simulated. Finally, the equivalent sound levels, standard deviations, traffic noise indexes and frequency distributions under the two different traffic flow conditions are compared and analyzed, and several important difference in traffic noise under the two different traffic flow conditions are obtained. Related Articles | Metrics

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The calculation analysis of high frequency vibration of railway vehicle wheel by using 2D axisymmetric model 2010, 30(6): 114-118.  Abstract ( )   In this paper, the modal analysis of the railway vehicle wheel is calculated by using 2D axisymmetric model. Based on the calculation results, the receptance of the wheel, standing for vibratory response of wheel, is provided according to modal superposition theory. In the calculation, not only the wheel’s elastic modes but also the wheel’s rigid body modes are taken into consideration. Besides, this paper make an in-depth analysis of characteristics of vibratory response calculated according to modes of wheel and modes of wheelset respectively, and, on the basis of which, the improving methods are presented. The results show that the modes involving axle and the rigid body modes have influences on the dynamic response below 2000 Hz band. The vibratory response of the wheel, calculated by modifying modal damping ratio of single wheel, is in good agreement with the calculation result of wheelset in the frequency range above 1000 Hz band. Related Articles | Metrics

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Noise Test and Analysis of Different Line Forms of 350km/h High-speed Train 2010, 30(6): 119-122.  Abstract ( )   In order to investigate the noise level of different line forms of 350 km/h high-speed train in operation, the noise intensity is tested and analysised on three line forms of Beijing-Tianjin Passenger Dedicated Railway, which includes the bed, the viaduct and the bed-viaduct transition. The result indicates that the noise level radiated by train when running on the viaduct is the lowest and the noise level radiated by train when running on the bed-viaduct transition is the highest. The result is significant for noise reduction design of the express train-sets. Related Articles | Metrics

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Ship’s seismic-wave field research and the real-time detection system 2010, 30(6): 123-126.  Abstract ( )   The concept and theory of the ship seismic-wave field are introduced. The real-time detection system that based on Labview is designed. The configuration and operating principle are also introduced. The convenience and flexibility of the system are represented during the system-test. The experiment results from trial show the andvantage of ship seismic-wave field in the target detection and recognition. Related Articles | Metrics

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The relationship of vibration-noise between pipe and ship Liang xiangdong 2010, 30(6): 127-128.  Abstract ( )   In this paper, we developed the relationship between pipe vibration-noise and ship noise. We introduced the main reason that excites the ship sonar platform self-noise is the pipe noise caused by hydrodynamic power in the pipe. At the end of this paper, we introduced some suggestions for controlling this kind of pipe vibration and noise. Related Articles | Metrics

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Calculation and analysis of transverse vibration of the bending shaft 2010, 30(6): 129-131.  Abstract ( )   Related Articles | Metrics

5.建筑振动与建筑声学

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The facture of the dodecahedron loudspeakers Cai Yang-Sheng 2010, 30(6): 132-135.  Abstract ( )   The dodecahedron loudspeakers is one kind of the sound source in building acoustics measurements. The difficult of the facture is to comfirm the directivity of theloudspeaker. The loudspeaker with the same directivity in plane and vertical is created in EASE software,the directivity of the dodecahedron loudspeakers is simulated The dodecahedron loudspeakers is manufactured based on the simulated result.At last the directivity of the manufactured dodecahedron loudspeakers has been measured,and it is accord with the related standards. Related Articles | Metrics

6.信号处理与故障诊断

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Identification base on Improved Maximum-Likelihood for Random Noise Nonlinear System Hou Yuan-bin;Li ning Li 2010, 30(6): 136-139.  Abstract ( )   Aim at nonlinear character of the aeration machine with random noise disturbing, an improved maximum-likelihood estimation（IMLE）is proposed. In unknown covariance matrix, one step difference of the loss-function is changed into searching optimization probability of the two-dimensional loss-function, namely, according as the statistical minimum loss-function, the random point-circulation is located, searching minimum in hiding function of loss-function, the IMLE method with the random point-circulation is built. Then the nonlinear parameters of the 560KW aeration machine are identified for random noise disturbing of global field for mine-dirt. Simulation result validates that identification error is decreased to 0.1% from MLE 35% under same condition at the aeration machine running of power plant, this improved method has higher identification ability than the general MLE. Thereby the aeration machine system is rebuilt; by high-pressure frequency conversion, the result of save energy is overt. Related Articles | Metrics

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LabVIEW-based near-field acoustical holography Noise Source Identification System 2010, 30(6): 140-144.  Abstract ( )   Since most of the noise source identification systems are high cost, in this paper a near-field acoustical holography noise source identification system based on LabVIEW is developed, which is low-cost and more practical compared with the current ones. Based on the proposed system, the acquisition method of array snapshot can be used when having a larger number of microphones; also the scanning method can be used when the number of microphone or the instrument channel is limited. Through the embedded matlab calculation program of near-field acoustic holography, the sound field can be reconstructed and predicted, at the same time the reconstruction and prediction can be displayed through LabVIEW visual controls. In the paper, the principle and the realization process of the proposed system is firstly introduced, and then its validity is verified by the experiment. Related Articles | Metrics

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Noise reduction of acousto-ultrasonic signals 2010, 30(6): 145-148.  Abstract ( )   There are much systemic and environmental noise in acousto-ultrasonic signals, which seriously affect the read of actual signals . So take the method of even filter and wavelet packet transform to reducing noises. Then, a wavelet noise reducing model was formed by the two-rank Daubechies wavelets function.The results show that after the processing noise can be removed obviously and the useful signals can be reserved compeletely. Related Articles | Metrics

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Parameter identification and anti-synchronization for uncertain hyper-chaotic system He wansheng 2010, 30(6): 149-152.  Abstract ( )   A parameter observe is designed to identify a hyper-chaotic system with unknown parameters. Based on Lyapunov stability ,the suitable controller were given to realize anti-synchronization for the unknown parameters of hyper-chaotic system. Theory analysis and numerical simulation results show that the observers and controller were effective and feasible. Related Articles | Metrics

8.标准规范与评价

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Benchmark Location Application in Engine Vibration Signal Analysis 2010, 30(6): 153-156.  Abstract ( )   From the point of view of engine vibration signals, the relationship of vibration signals, instantaneous fundamental frequency and crank angle at a certain time in time domain have been studied, presenting a method of positioning stimulus-response signals of the engine surface accurately with the instantaneous fundamental frequency as a reference, and the application example of using fault signature to diagnose abnormal valve clearance have been offered. Related Articles | Metrics

6.信号处理与故障诊断

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Study on the Machinery Condition Monitoring Method based on SVDD 2010, 30(6): 157-160.  Abstract ( )   A new method based on Support Vector Data Description（SVDD） was presented in this paper to accomplish the machinery condition monitoring. The data description template based on the normal samples was established. Then, the fault identification and classification were realized by calculating a parameter named the change rate of distance. The feasibility of this method was verified by experiment. The experiment results show that the condition monitoring model proposed in this paper is autoregulation according with the condition change of machinery , and the retraining times of the model is reduced. Related Articles | Metrics

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Separation of Mechanical Vibration Signals Including Additional Noise Based on Blind Source Separation 2010, 30(6): 161-164.  Abstract ( )   There are two problems in identification of mechanical mechanical vibration signals of the underwater navigation object. Firstly, the vibration signals are coupling mutually. Secondly, the vibration signals can not be measured by sensors. In this paper, the additional noise was regarded as an independent source signal and the mathematics model of BSS for the instantaneous mixed signals was proposed. With the double decorrelaion blind separation algorithm, the mixed vibration signals including the additional noise were separated . Finally, the feasibility of the algorithm was testified by the separation simulation of the vibration signals including the additional noise. Related Articles | Metrics

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Application of Wavelet Analysis to Multiple Faults Diagnosis in Rotor Shaft System SONG Zheng 2010, 30(6): 165-170.  Abstract ( )   This paper developed a new method to extract fault feature from the system, where multiple faults may occur simultaneously in the rotor shaft and bearing, with wavelet multiple-dimensioned decomposition. First, the levels of wavelet decomposition are determined by the fault feature frequency, and the time domain characteristic parameters of HF detail signals, which could show the fault characteristic, are calculated. Then, these parameters are compared to the normal ones, by which the fault and its source can be identified. Multiple-dimensioned decomposition can improve the signal-to-noise ratio (SNR) of fault signals obviously. Because both of the time and frequency domain information of the fault are taken into account, with the distribution of vectors made up of characteristic parameter, different source of fault can be diagnosed at the same time. The validity of this method was proved by massive simulations and fault bearing examples. Related Articles | Metrics

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De-noising Algorithm of Hydraulic System Fault Signal Based on Wavelet Entropy 2010, 30(6): 171-174.  Abstract ( )   Abstract：Abstract：Aiming at the require of fault diagnosis and signal characteristic, a new de-noising algorithm based on wavelet entropy is proposed. The idea of the algorithm is that using the wavelet entropy judges the frequency band of useful signal, reconstructs the coefficient in this frequency band and then the de-noising signal is obtained. The new algorithm and the threshold de-noising algorithm are used in the pressure signal of hydraulic system, the de-noising results prove that the new algorithm is more valid than the threshold de-noising algorithm. Related Articles | Metrics

7.减振降噪设备和器材

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Optimizing design on parameters of Aluminum Foam Impact Energy-absorption Implement 2010, 30(6): 179-182.  Abstract ( )   The paper conducts the design and predigestion on installation mode of aluminum foam energy-absorption implement. With the help of MATLAB optimize toolbox, the mathematics model of aluminum foam energy-absorption implement is established, calculating the mathematics model and educing parameters of the energy-absorption element after optimizing. The study demonstrates that the energy-absorption property and stability of the energy-absorption implement enhanced, and specific energy absorption will also enhance, the optimizing effect is quite prominence. The optimizing design of this paper will provide trustiness use for reference and feasible theory gist for designing and empoldering foam-filled energy-absorption implement. Related Articles | Metrics

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Test-study on Al foam energy absorber passive-shock-isolation technology 2010, 30(6): 183-188.  Abstract ( )   Warships and onboard equipments must face various shock problems caused by contact blast, non-contact blast and its own weapons emission. Referring to BV043/73 standard of Germany, a passive shock isolation technology using the Al foam energy absorber is investigated and tested in this paper, these results demonstrate that the application of Al foam impact energy absorber can effectively avoid secondary impact of the equipment and its application is feasible. Some results are put forward, which give useful advices for the engineer application. Related Articles | Metrics

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The Acoustic Performance Analysis of Concentric-tube Resonator with Perforated Baffle 2010, 30(6): 189-191.  Abstract ( )   According to the civil aircraft APU (Auxiliary power unit) exhaust muffler configuration, one perforated baffle was applied in the Sullivan concentric-tube resonator model. When do the acoustic analysis of the perforated baffle concentric-tube resonator using software Virtual. Lab-FEM, the results shows that a good Transmission loss was found in the low frequency comparing with the non-perforated baffle. Related Articles | Metrics

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Study on the Transfer Characteristics and Impedance of Air-spring with Rubber Bellow 2010, 30(6): 192-194.  Abstract ( )   A test rig is designed. The input and transfer impedance of air-spring with rubber bellow at different pressure and height are tested and its transfer characteristics are analyzed systematically. The testing results indicate that the vibration isolation performance of the air-spring is excellent and no “wave effects” occurs in high frequency. If the working height is constant, the force transmissibility of air-spring with higher working pressure is smaller. If the working pressure is constant, the force transmissibility gets the minimum at the rated height. Related Articles | Metrics

9.振动噪声测试技术

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《Error Analysis and Experimental Research on Measuring Damping materials Based on Phase Method》 2010, 30(6): 199-202.  Abstract ( )   The measuring principle of visco-elasticmeter based on the phase method is analyzed theoretically. It is explained that the effect of the mass of fixtures to fix the test specimen must be considered when measuring Young’s modulus (E) of rubber. The small mass, the high stiffness and low loss factor of the fixtures are helpful to raise the measuring precision. An experiment is made with the self-made system working on the phase method and the results from the experiment are in accordance with the theoretical analysis. Related Articles | Metrics

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Experimental Study on Sound Pressure Distribution of Air-blast Atomization Flame Shen Bin 2010, 30(6): 203-208.  Abstract ( )   Sound pressure distribution of air-blast atomization flame was studied. Relationship between flame length and sound pressure distribution was established and influence of different flame length on the radiation characteristics of flame noise was analyzed. Results show that flame noise sound pressure field can be divided into three regions according to the flame length L: near-field zone, attenuation zone and far-field zone. Near-field zone is the generation area of air-blast atomization flame noise, where the value of sound pressure is the largest and combustion noise is the main noise source. Attenuation zone can be used as the best noise sampling area, in which the total sound pressure can be measured. Far-field zone changes in the value of sound pressure is very small and the value can be approximately equal to the far-field sound pressure. With the increase in flame length, the direction of flame noise is more obvious and the radiation intensity is greater. Related Articles | Metrics

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Testing Analysis of Reducing Vibration for the Motor 2010, 30(6): 209-210.  Abstract ( )   Abstract:Single Phase asynchronous motor is widely used in our life, but the vibration is a big problem, and good or bad vibration is an index to decide the motor. It is solved the vibration problem through the vibration testing and analysis in this paper. And judge the dynamic balance of the rotor through the method of seeing the vibration magnitude at rotational frequency. And then solve this vibration problem Related Articles | Metrics

10.工程实践

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Sound Insulation Design and Experiment in Researching 30kW Mobile Power Station 2010, 30(6): 211-213.  Abstract ( )   As designed 30kW low noise mobile power station, the noise of the combustion engine power station is decreased when the sound insulation, absorption and elimination technology is utilized, and the problem of the ventilation and head radiation of the combustion engine is solved. The sound insulation and elimination is calculated used the mathematic model of restraining the noise technology, the noise label of the low noise power station is estimated, the design cycle is decreased. It is proved through the experiment that the sound insulation design is completely and the noise reduction result is satisfied. Related Articles | Metrics