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18 October 2012, Volume 32 Issue 5 Previous Issue    Next Issue

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封面、目录 2012, 32(5): 0-0-1.  Abstract ( )   PDF (428KB) ( )   Related Articles | Metrics

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State of the Research on Model for Road Roughness Excitation XIA Jun-zhong 1, MA Zong-po 1, BAI Yun-chuan 1, SU Tao 1, LENG Yong-gang 2 2012, 32(5): 1-5.  DOI: 10 3969/j.issn.1006-1335.2012.05.001 Abstract ( )   In view of various methods and complex classifications for road surface excitation models, the characteristics, differences and scope were analyzed in both stationary model and non-stationary model. The applications of some new theories and methods in stationary and non-stationary simulation of road roughness were introduced. Then pointed out the problems and shortcomings of current research and made prospects for future research directions in this field. Related Articles | Metrics

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Some Progress of the Research of Vibration and Noise Control Technology for Submarine SUN Wei-hong,YAN Xin 2012, 32(5): 6-10.  DOI: 10 3969/j.issn.1006-1335.2012.05.002 Abstract ( )   Vibration isolation and noise control technology is widely used nowadays in most of submarines, that minimizes the underwater acoustic signature that the submarine radiated so that the submarine is difficult to be detected by enemy’s shipboard sonar. In this paper, the sources of vibration and noise in submarine are analyzed, and some of the latest research progress of vibration control, active and passive noise elimination technology for submarine are reported. Finally an outlook to the development tendency of submarine noise and vibration control technology is presented. Related Articles | Metrics

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Reviews of Vehicle Noise Source Identification Methods HU Yi-xian,LI Shun-ming,ZHANG Yuan-yuan,MENG Hao-dong 2012, 32(5): 11-15.  DOI: 10.3969/j.issn.1006-1335.2012.05.003 Abstract ( )   In the vehicle industry, noise issues have become more evident. Vehicle noise source identification is an important prerequisite for noise control. In recent years, new methods of vehicle noise source identification have been developed, but it is necessary still for them to improve and optimize. The different methods for identifying noise sources are reviewed in this paper. All methods are divided into three categories, i. e. the traditional analysis method, the method based on signal processing, and method based on acoustic array technology. The features of various identification method are described and compared. Finally, some prospects of noise source identification method are given. Related Articles | Metrics

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Review of Soundscape SONG Jian-wei, MA Hui，FENG Yin 2012, 32(5): 16-20.  DOI: 10.3969/j.issn.1006-1335.2012.05.004 Abstract ( )   The concept of soundscape appeared in the end of last century. With developing of environment acoustics and increasing of requirement on improving sound environment, soundscape has been being studied more and more in order that the idea of soundscape could be used in practice. Variation of the contents of soundscape research, the improvement of research method and the state of art at home and abroad were reviewed systematically in this paper. Furthermore, the problems facing us are pointed out for reference. Related Articles | Metrics

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Finite Difference Method Simulation of the Sinusoidal Acoustic Signal Propagation in Drill String Structure LIU Yong-wang,GAUN Zhi-chuan,LONG Zhi-qiang,ZHAO Guo-shan,DU Bin-bin 2012, 32(5): 21-25.  DOI: 10 3969/j.issn.1006-1335.2012.05.005 Abstract ( )   The drill string is simplified as ideal periodic tube structure. Finite difference method is employed to simulate and analyze the phenomenon of large differences between transmission coefficient and attenuation coefficient during transmission process of sinusoidal signal of different frequency along the periodic tube structure. The distributions in time domain and frequency domain respectively of the signal after transmission through the periodic tube structure from sine signal of different frequency through the periodic tube structure are obtained. Then using this method the transmission of sinusoidal acoustic signal of 400 Hz and 500 Hz in a periodic tube structure. has been simulated. The results show that waveform distortion and spectrum variation are small and transmission is good for the sinusoidal signal of pass band frequency, but waveform distortion is severe, spectrum variation significant and transmission are bad for the sinusoidal signal of block band frequency. The simulation results have good nstency with that of other similar research. The feasibility and validity of the finite difference method presented in this paper are verified. Related Articles | Metrics

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Design and Simulation of Double-stage Active Vibration Isolation System Based on Voice Coil Motor 2012, 32(5): 26-30.  DOI: 10.3969/j.issn.1006-1335.2012.05.006 Abstract ( )   Taking voice coil motor (VCM) as the actuator of active vibration isolation system, the operational mechanism and features of VCM are introduced, its mathematical model is set up, and transfer function is deduced. Then the model for double –stage vibration isolation system are established. A broadband active vibration isolation system using VCM as actuator has been designed for the goal to get minimum displacement transmissibility. Finally, the results from simulation by Matlab/Simulink show that this vibration isolation system offers very good performance of vibration isolation in rather broad frequency range. Related Articles | Metrics

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Wave Superposition Method for Reconstruction of Cylindrical Shell Radiated Sound Field 2012, 32(5): 31-36.  DOI: 10.3969/j.issn.1006-1335.2012.05.007 Abstract ( )   Near-field holography based on wave superposition method (WSM) is used for reconstruction of sound field radiated by underwater structure. By theoretical deduction and numerical simulation, the effectiveness of reconstruction and the factors to affect reconstruction accuracy are analyzed by using a cylindrical shell model with spherical endcaps. Considering the situation of practical application, a cylinder holographic surface and two parallel plane holographic surfaces are used. The simulation results demonstrate that this method can be robustly applied to sound field reconstruction for whole wave number space. The accuracy is affected by the parameters of virtual source surface, holographic surface and SNR(signal / noise ratio). On the condition of noise measurement, the sound field can be reconstructed more accurately by using Tikhonov regularization method with L curve. Compared with other methods, WSM is better featuring less measurement points and quicker calculation speed, and promising in application. Related Articles | Metrics

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Numerical Computation of Structure Radiated Acoustic Field Using Boundary Meshless Method 2012, 32(5): 37-41.  DOI: 10 3969/j.issn.1006-1335.2012.05.008 Abstract ( )   The general requests of finite-dimension approaching interpolating shape functions are presented, the method and procedure of construction of the meshless interpolating shape function using moving least square method are introduced. The point collocation method was adopted to discretize the Kirchhoff-Helmholtz boundary integral equations into linear equation groups that constrained by boundary conditions. Constrained equation groups were solved by matrix-division method, and then the discrete numeric expression of acoustic radiating and transferring model was obtained. In the example, acoustic field was calculated by the acoustic radiating and transferring model that obtained through both BMLM and BEM, and the comparison between the results of numerical computation and that of analysis shows that the interpolating functions of boundary meshless method self-constructed are more flexible and of higher accuracy of interpolation and calculation. Related Articles | Metrics

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Simulation of Sound Radiation Characteristics and Structure Optimization of a Gear Pump 2012, 32(5): 42-45.  DOI: 10.3969/j.issn.1006-1335.2012.06.009 Abstract ( )   The finite element model of structure of a gear pump is established with software Hypermesh, and the inherent vibration modes are extracted. By using software LMS.Virtual. Lab the frequency response and accelerations at all nodes are gained based on its modes. In the calculation of acoustic BEM (boundary element method) module direct BEM has been used to find out acoustic responses at standard field points. Results show that sound radiation characteristics of the gear pump correlate with its modal shapes. For reducing noise radiated by the gear pump a modification program of the gear pump’s structure has been proposed. Related Articles | Metrics

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Bifurcation Analysis of a Constrained Cantilevered Pipe Conveying Fluid under the Harmonic Parametric Excitations 2012, 32(5): 46-48.  DOI: 10.3969/j.issn.1006-1335.2012.05.010 Abstract ( )   The bifurcation behavior of the cantilevered pipes conveying pulsating fluid is investigated by taking into the nonlinear factors of Dirac delta account. The partial differential equation are discretized via the Galerkin’s method, and lead to a set of ordinary differential equations (ODEs). The ODEs is numerically solved by a fourth order Runge-Kutta scheme. Attention is concentrated on the possible bifurcation of the system with a different govern dimensionless parameters. The route to chaos is shown to be via period-doubling bifurcations. Finally, the cumulative effect of frequency on the dynamics is discussed in the different dimensionless flow velocity. Related Articles | Metrics

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Study on Vibration Characteristics of Constrained Damping Structure with Considering of Parameter Randomness 2012, 32(5): 49-52.  DOI: 10.3969/j.issn.1006-1335.2012.05.011 Abstract ( )   In this paper the finite element model of constrained damping structure was established based on modal strain energy theory. In study of vibration characteristics the effects of the thickness of viscoelastic layer and randomness of material parameters on natural frequencies and modal loss factors of constrained damping structure were analyzed. The results show that the analysis of material parameter rendomness of constrained damping structure is necessary, the analysis method and conclusions made in this paper may be benefits for engineering practice. Related Articles | Metrics

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Oil Film Whirl Dynamic Characteristics and Influence Factors in High Speed Rotor-bearing System DOU Wei1, ZHANG Nan1,WU Nai-jun1, LIU Zhan-sheng2 2012, 32(5): 53-58.  DOI: 103969/j.issn.1006-1335-2012-05-012 Abstract ( )   The dynamic model of rotor-bearing system under the action of non-linear oil film force is established for a practical rotor-bearing system supported by sliding bearings. With application of nonlinear dynamics theory, system response was simulated numerically. The effects of eccentricity, speed, lubricant viscosity, radius gap, bearing length and journal radius on oil film whirl and system response were obtained by using amplitude-frequency curve, bifurcation and three-dimensional spectrum. This is of value for reference to design optimization, fault diagnosis and vibration control of rotor system in engineering practice. Related Articles | Metrics

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Study on Local Flexibility Coefficient of Pipe with Some Surface Circumferential Crack 2012, 32(5): 59-61.  DOI: 10.3969/j.issn.1006-1335.2012.05.013 Abstract ( )   Based on the method, i.e. change integration section method for local flexibility coefficient of the pipe with line crack presented by Zheng etc., the surface circumferential crack section is devided into a series of rectangular strips, each strip is treated approximately as a plane crackle beam to calculate its strain energy by using stress intensity factors. The expression of local flexibility due to circumferential crackle on pipe’s surface is obtained and verified by using the existing experimental data in this paper. Related Articles | Metrics

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Dynamic Characteristics of Feedback Coefficient of Single Magnet Suspension Control System 2012, 32(5): 62-66.  DOI: 10.3969/j.issn.1006-1335.2012.05.014 Abstract ( )   Single magnet suspension system is the most simple and fundamental unit in maglev train research. To investigate the effects of feedback coefficient of maglev train control system on stability of the maglev train, the “single magnet-track-suspension”system reference model has been established. Through deduction of its dynamic equation and introduction of the law of state feedback control, the physical meaning of each feedback coefficient in the law on the suspension system was revealed. It is shown by comparison with ordinary 2-order vibration model that change of clearance feedback coefficient means change of suspension stiffness, change of speed feedback coefficient means change of suspension system damping, and change of acceleration feedback coefficient means change of suspension system mass. The observer for state of single magnet suspension system was designed mathematically. It is found that the vibration response of the suspension system is not significant for high frequency excitation, but notable Related Articles | Metrics

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The Characteristics of Vertical Bending Vibration and Sound Radiation of Underwater Vehicle 2012, 32(5): 67-71.  DOI: 10.3969/j.issn.1006-1335.2012.05.015 Abstract ( )   Vertical bending vibration mode is one of the common vibration modes of underwater vehicle structure. To control bending vibration is an important task in design of underwater vehicle. The equations of bending vibration and acoustic radiation of the underwater vehicle were established based on the theroy of FEM/BEM with considering sound-structure coupling effects, the natural frequencies and forced vibration responses were calculated numerically to find out the cheracteristics of sound radiation induced by vertical bending vibration, and the characteristics of sound radiation by the excitation velocity of the value on restriction line in vibration criteria graph were discussed. The results show that vertical bending vibration does bring about significant noise, and the contribution of first and second vibration modes is dominant in sound radiation. For reducing line spectrum the vibration response at low frequencies must be lowered. In design of structure vibration control, additional criteria should be prosed specially for reducing bending vibration induced sound radiation except that for vibration severity. Related Articles | Metrics

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Analysis and Discussion on Vertical Directivity of Ship Radiated Underwater Noise 2012, 32(5): 72-75.  DOI: 10.3969/j.issn.1006-1335.2012.05.016 Abstract ( )   Based on the data of noise underneath a tugboat measured by a line array system, and with relevant data processing and analysis method the vertical directivity of tugboat’s radiated noise was analyzed to get the typical vertical directivity pattern of total sound level and line-spectrum. Related Articles | Metrics

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Noise Characteristic of Cross-sit-monorail Train 2012, 32(5): 76-78.  DOI: 10.3969/j.issn.1006-1335.2012.05.017 Abstract ( )   B&K 2250 handheld precision noise analyzer is used to measure the noise data of cross-type monorail train, then the noise propagation pattern and the spectrum are gained as well. The results show that low-frequency part of the energy of the Chongqing monorail train noise is small. Compared to that of B-type wheel-rail train, the noise level of cross-sit-monorail train is significantly lower at the same speed. Related Articles | Metrics

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Vertical Vibration Analysis of Flexible Car-body Based on Simulink WANG Hui, ZHONG Xiao-bo,SHEN Gang 2012, 32(5): 79-82.  DOI: 10.3969/j.issn.1006-1335.2012.05.018 Abstract ( )   The oscillatory differential equation of the car body was given with the principle of modal superposition by considering car body’s vertical elasticity, and mathematic model of a rigid-flex railway vehicle was established using MATLAB/Simulink. With this model, the influence on the vertical vibration characteristics of the elastic natural frequency, damping factor and the velocity was researched. Based on the analysis above, a new concept, ride-performance resonant wavelength, was proposed. The concept, which was proved to be one of the vehicle’s inherent features, can be the guideline and evaluation basis for the vehicle design and line maintenance. Related Articles | Metrics

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Testing and Diagnosis for Cab’s Vibration of a Light Truck 2012, 32(5): 83-87.  DOI: 10.3969/j.issn.1006-1355.2012.05.019 Abstract ( )   Through vibration measurements and the analysis of vibration transmision pathes for the cab of a light truck it is shown that the vibration is attributed to suspension system problems, i. e. to say that vibration reduction property of the suspension system of its power train is not adequate for lateral vibration excitation. By using new modified suspension system the cab vibration is effectively controlled, and the analytical results of above have been verified. Related Articles | Metrics

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Characteristics of Interior Sound Field of 3 t Forklift Cab 2012, 32(5): 88-91.  DOI: 10.3969/j.issn.1006-1335.2012.05.020 Abstract ( )   After establishing 3-dimension finite element model for 3 t forklift cab structure and the acoustic finite element method for the interior acoustic field inside the cab, structural modal analysis and acoustic modal analysis are carried out respectively for the cab. The displacement response data gained from dynamic response analysis offer boundary condition for following acoustic field analysis. Spectrum analysis of SPL (sound pressure level) in the interior field, especially SPL at ear position was carried out. Contributions to the sound field from vibration of each cab panel are analyzed to find out the main sources for the peak value of SPL as reference for noise control purpose. Related Articles | Metrics

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Parameter Self-tuning Fuzzy Control of Semi-active Suspension for Rigid/Flexible Coupling Train Model 2012, 32(5): 92-96.  DOI: 10.3969/j.issn.1006-1335.2012.05.021 Abstract ( )   In order to reduce the lateral vibration of train, the FEM model in ANSYS is set up and the modal neutral file is introduced into ADAMS/Rail to establish the ragid/flexible coupling dynamic model of car body of the train which considering lateral elastic vibration. The influence of elastic vibration on running smoothness of the train is analyzed. The method of parameter self-adaptive fuzzy control is presented in which the front and rear acceleration of car body was taken as control goal and feedback of the double close-loop system. The co-simulation results show that the vibration calculated by rigid/flexible body model are much greater than that by ragid body model, and the lateral vibration of car body may be reduced effectively by using self-adaptive fuzzy control method which is better than the common-used fuzzy control method. Related Articles | Metrics

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Vibration Characteristics of a Vehicle Exhaust System 2012, 32(5): 101-103.  DOI: 10.3969/j.issn.1006-1335.2012.05.023 Abstract ( )   In this paper the finite element model of the exhaust system of a vehicle is established for modal analysis simulation, the natural frequencies and modal shapes of first several orders are obtained . Based on modal analysis and the results of vibration test of the exhaust system , vibration characteristics of the exhaust system at different engine speed are analyzed and the suggestions to improve the structure are given for reference to enhance operational reliability and service life of the exhaust system. Related Articles | Metrics

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Measurement and Analysis of Sound Radiated from a Single Vehicle 2012, 32(5): 104-109.  DOI: 10.3969/j.issn.1006-1335.2012.05.024 Abstract ( )   The sound radiation model of the moving point source, single vehicle in a semi-free acoustic field is obtained for the research of road traffic noise. The acoustic characteristics of the noise radiated from single vehicle in real road conditions, such as sound level, signal in time domain, spectrum and sound quality etc., are discussed by means of noise measurements and related acoustic evaluations. The results show that the sound level radiated from single vehicle changes nonlinearly, i. e. increases first and then decreases with the distance from the vehicle to testing spot. The sound level of high frequency component attenuates more and more remarkably as the distance increases. Low frequency components with higher level are more predominent for the noise of middle and heavy car than that of small car. Regarding loudness the contributions at 125 Hz and 1 kHz for small car and that at (250～500) Hz for heavy car are predominant. Related Articles | Metrics

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Vertical Propagation Regularity of Road Traffic Noise 2012, 32(5): 110-113.  DOI: 10.3969/j.issn.1006-1335.2012.05.025 Abstract ( )   The vertical propagation regularity, i. e. noise level going up first and then down with height, is verified through measurements of the noise level outside the window on site of six street buildings. For reasoning of the regulariy, analysis of measured data, theoretical computation and application of noise prediction software Cadna/A were combined. It is shown that the vertical propagation regularity of road traffic noise correlates with the features of road itself. The noise level increases under certain height, but beyond that height the noise level will attenuate according to line source theory. Related Articles | Metrics

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Difference between Results by Pure Tone and That by Noise as Signal Source in Free Field Measurements 2012, 32(5): 114-117.  DOI: 10.3969/j.issn.1006-1335.2012.05.026 Abstract ( )   The choise of pure tone or noise as signal source in the measurement of free field deviation of anechoic or semi-anechoic room will affect the results of measurements. By using anechoic room free field deviation model in first-order reflection condition, the difference of the results measured by the two kind of signal was deduced. Through comparison, the deviation law  of free field are obtained, which verifies the analytical model used and gives a good reference for the choice of signal source in free field measurements. Related Articles | Metrics

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Study on Noise Prediction Model for Wind Power Field 2012, 32(5): 118-122.  DOI: 10.3969/j.issn.1006-1335.2012.05.027 Abstract ( )   The Hubbard wind noise prediction model was applied for prediction of wind turbine generator noise. According to the measured noise data of domestic operating wind turbine sets, modification of parameter Ka, near field sound level correction in tower height’s distance and wind direction correction were proposed to improve prediction with Hubbard model. Comparison of calculated results by using modified Hubbard model with that of measurements from 3 wind power field showed that the modified Hubbard model had a better prediction accuracy for noise distribution in wind power field . Related Articles | Metrics

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Study on Characteristics of Noise Environment at Bus Stops      in Beijing 2012, 32(5): 123-126.  DOI: 10.3969/j.issn.1006-1335.2012.05.028 Abstract ( )   For investigation of noise environment at bus stops in Beijing measurement and analysis of noise data at 14 bus stops of bus No.67 were taken. The results show rather high level LAeq  with 76.5 dB(A) in average, 78.5 dB(A) peak. The background noise level was 67.1 dB(A). It is found by spectrum analyses that low frequency components are predominant in this kind of noise environment with some apparent tones at 31.5 Hz and 80 Hz. The peak around 8kHz in high frequency appears representatively. Related Articles | Metrics

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Application of building enclosing constructer in sound insulation 2012, 32(5): 127-130.  Abstract ( )   The purpose of this article is to study the application of building enclosing constructer for coal mine ventilation shaft noising controlling to insulate noise, to eliminate the noise pollution and to reduce engineering costs. By analyzing and comparing the noising insulation characteristic of different enclosing constructer, the author discuss the feasibility of using those constructer to insulate different noising source .Both light-duty and heavy-duty building enclosing constructer all can be widely used in noise controlling for their small noising leak coefficient. Depends on the different sound insulation characteristic, the inclosing constructer are made into soundproof room, soundproof shade and acoustic septum, all of those can hinder the noise spreading. This technology is used in coal mine ventilation shaft for electric motor, fan and vent noise controlling, all get good sound insulation effect, which can guide the design of similar noise controlling engineering. Related Articles | Metrics

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Elementary Analysis of HVAC System Noise on Offshore Platform ZHANG Hui-fang1,ZHANG Yong-qing 1, CHEN Zi-gang1,XIE Li-jun1,WANG Yu2 2012, 32(5): 131-135.  DOI: 10.3969/j.issn.1006-1335.2012.05.030 Abstract ( )   For the purpose of noise control, the sources and mechanism of the HVAC (Heating Ventilation and Air Conditioning) system noise on offshore platform were analyzed. It is shown that besides the HVAC system noise there are ambient noise and the secondary noise radiated by piping system, and based on the theory of noise control, the measures of noise reduction were proposed. Results of this research provide some reference for noise control of offshore platform HVAC system, and also have a guiding significance for HVAC system design in the field of marine engineering. Related Articles | Metrics

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Study on the Distribution of Sound Field in Vertical Plane of Traffic Noise for City Elevated Complex Road 2012, 32(5): 136-140.  DOI: 10.3969/j.issn.1006-1335.2012.05.031 Abstract ( )   By using software Cadna / A the distribution patterns of sound field in vertical plane of  traffic noise for elevated complex road in different road conditions are analyzed. Owing to changing of the distribution pattern of sound field in vertical plane by viaduct it is in need to analyze the effects of viaduct in different road conditions. A large amount of noise barriers had been built on viaduct in China with not definite value of noise reduction. In this paper the noise reductions of barriers in different road conditions were calculated and analyzed. The results help to make right decision for building viaduct noise barriers effectively according to different road conditions. Related Articles | Metrics

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Analysis of Noise Characteristics on Metro Station Platform 2012, 32(5): 141-143.  DOI: 10.3969/j.issn.1006-1335.2012.05.032 Abstract ( )   The noise environment on platform of metro station is investigated for platform conditions as the train goes in, goes out and without train respectively by measurements using noise and vibration analysis system. The results show that superposition of weeltrack noise and squealing noise of braking is predominant in noise sources, and the equivalent noise level is 81.5 dB(A), frequency range 200～4 000 Hz when train goes in. For the platform without train the equivalent noise level measured is 79.1 dB(A), 500～1000 Hz mainly from broadcast in the station. These data are of value for reference in noise control design of metrostation. Related Articles | Metrics

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Local Mean Decomposition and Its Application to Rotating Machinery Composite Fault Diagnosis 2012, 32(5): 144-149.  DOI: 10.3969/j.issn.1006-1335.2012.05.033 Abstract ( )   For the non-stationary characteristic of vibration signal in rotating machinery composite fault diagnosis an analysis method based on LMD(local mean decomposition) was developed. Firstly, the original vibration signal was decomposed into several stationary PF (product function) plus a residual component by using of LMD，then the main components in fault signal were determined by calculation of  correlation factor of each PF with the original signal . Finally，the features of shaft fault were extracted by Fast Fourier Transform of low-frequency components, and the features of bearing fault were extracted by envelopment spectrum analysis of high frequency componants. The effectiveness of the method is also proved by analysis to composite fault vibration signal of a gear box. Related Articles | Metrics

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The Application of Envelope Spectrum on Shock Fault Diagnosis of the Power System 2012, 32(5): 150-153.  DOI: 10.3969/j.issn.1006-1335.2012.05.034 Abstract ( )   In this paper the necessity of introducing VMDT(vibration monitoring and diagnosis technology) into torpedo power system CMFD(condition monitoring and fault diagnosis) is analyzed. The CMFD method using time-varying parameter combining with envelope spectrum for detecting shock fault of reciprocating mechanism is proposed.. The engineering application cases show that the symptom of shock fault prior to it’s occurrence could be detected by using the time-varying parameter analysis method based on RMS (root-mean-square), and the shock fault frequency which is used to determine the fault type and position is possible to be extracted by the envelope spectrum method based on Hilbert transform. This is significant to promote the practical application of VMDT in torpedo power plant tests and improve operation safety. Related Articles | Metrics

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Implementation and Application of Short-time Fourier Transform Based on FPGA 2012, 32(5): 154-158.  DOI: 10.3969/j.issn.1006-1335.2012.05.035 Abstract ( )   Aiming at the demand of signal processing in real-time machinery monitoring, a program of implementation of a short-time Fourier Transform with FPGA (Field Programmable Gate Array) based on the study on Goertzel recursive algorithm and its filter structure is presented in this paper. This program makes best use of embedded RAM resource, multiplier of FPGA and its flexible IP core function. The simulation signal and practical engineering signal are both tested, and the correctness of this program is verified. Related Articles | Metrics

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Method of Engine Fault Diagnosis Based on Kalman Transfer Matrix 2012, 32(5): 159-163.  DOI: 10.3969/j.issn.1006-1335.2012.05.036 Abstract ( )   In order to extract entire status features with high quality from the vibration signal on diesel engine cylinder head the forecasting algorithm based on kalman filtering is proposed to analyze time history of the signal.. A characteristic subset is made up by decomposition of singular value of transfer matrix through Kalman transfer matrix including entire engine state information. Considering the distribution at different working condition, the samples of a characteristic subset is classified and tested by use of extreme learning machine. It is shown by practical application that this algorithm offers higher precision for engine fault diagnosis. Related Articles | Metrics

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Application of Multi Sensor Information Integration οn Motor Fault Diagnosis 2012, 32(5): 164-167.  DOI: 10.3969/j.issn.1006-1335.2012.05.037 Abstract ( )   In order to improve the accuracy of motor fault diagnosis, a method of multi sensor information integration is applied. After the vibration spectrum signal collected with multi sensors processed, the ant colony algorithm-neural network was used to implement local fault diagnosis and acquire each other independent evidence, then the evidence theory was employed to fuse them. Ultimately diagnosis of motor faults was realized. Experimental results show that this method is effective to improve diagnostic reliability and reduces the uncertainty in motor fault classification and recognition. Related Articles | Metrics

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Identification and Elimination of Periodic Excitation in Operational Modal Analysis DENG Xian-lai, JI Guo-yi 2012, 32(5): 168-172.  DOI: 10.3969/j.issn.1006-1335.2012.05.038 Abstract ( )   Considering that periodic excitation normally exists in running machine the effects of periodic excitation on modal analysis results were studied by using numerical simulation. Through extracting the amplitude curve diagram from correlation function of response of the structure the modal components of harmonic response could be directly identified and the interference of periodic excitation elimilated by digital filtering technique The results of simulation test show that periodic excitation could be identified accurately by this method. This is of value in operational modal identification of linear stationary system. Related Articles | Metrics

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Fault Diagnosis for Valve Train of Diesel Engines Based on Exhaust Noise YIN Gang1,ZHANG Ying-tang1, LI Zhi-ning1,LI Jie-Ren2,ZHANG Guang1 2012, 32(5): 173-176.  DOI: 10.3969/j.issn.1006-1335.2012.05.039 Abstract ( )   The auto-regressive(AR) model of exhaust noise in diesel engine’s seven operating modes about the valve train was established. The auto-regressive parameters were regarded as the characteristic vectors to build the fault diagnosis model which was based on extreme learning machine. The proposed method was also compared with that of BP neural network, RBF neural network and support vector machine. Experimental results show that exhaust noise can be used for fault diagnosis in diesel engine’s value train. The classification accuracies of above four different intelligent methods are all higher than 95%. But the method of extreme learning machine has advantage apparently in training rate. Related Articles | Metrics

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The Influence of Inner Structure on Sound Absorption Properties of Porous Metal-fiber Material DING Yu-xiang，XU Ying，XU Ning 2012, 32(5): 177-180.  DOI: 10.3969/j.issn.1006-1335.2012.05.040 Abstract ( )   In this paper, the relationship between sound absorption properties of porous metal-fiber material with inner cavity, and the kind of inner medium, depth and position of cavity is studied. The results show that as medium is air the average absorption coefficient of is 0.62 which is higher than 0.58, that of structure without cavity. But as the cavity filled with sulfate the average absorption coefficient goes down to 0.52. As the depth of cavity increased from 3.5 mm to 6mm, the average absorption coefficient also increased from 0.53 to 0.56 with absorbtion band broadening. The closer of the distance from cavity to absorption surface, the better properties of sound absorption are gained. For the inner structure with many dispersed cavities, the absorption properties of material may be further improved. Related Articles | Metrics

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Study on Hardness and Friction Properties of New Type of Low-noise Water-lubricated Material for Ship Propeller Bearing 2012, 32(5): 181-184.  DOI: 10.3969/j.issn.1006-1335.2012.05.041 Abstract ( )   The hardness and friction properties of newly developed low-noise water-lubricated material for ship propeller bearing are investigated. For low-noise design requirements of the water-lubricated ship propeller bearing, the new type of water-lubricated material was made using nano-particle modified nitrile composite. The friction properties under dry and water lubrication conditions were measured. The results show that the friction coefficient of the newly developed bearing material with shore hardness 85A is less than that of the material with shore hardness 76A. This kind of material is of not only higher hardness but also better friction property to meet low –noise design requirements for ship propeller bearing. Related Articles | Metrics

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Optimization and Simulation of Foam Aluminum Mufflers HAN Bao-kun, LIU Wei, WU Tong-hua 2012, 32(5): 185-188.  DOI: 10.3969/j.issn.1006-1335.2012.05.042 Abstract ( )   The optimized design of foam aluminum foam muffler is carried out based on optimization software ISIGHT. The muffler performances before and after optimization of parameters, such as the length and diameter of inlet pipe, outlet pipe and idle pipe were simulated and analyzed with software FLUENT and SYSNOISE. The results show that sound transmission loss after optimization increases in average by about 5 dB, and pressure loss reduces by about 11 % comparing with that before. Consequently, the optimized foam aluminum muffler is of better acoustic and aerodynamic performance. Related Articles | Metrics

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The Effects of ThicknessVariation on Axial Stiffness of U-shaped Bellows XIU Zhu1,WANG Ji-min2, MA Jian-min 1 2012, 32(5): 189-192.  Abstract ( )   Stiffness is one of the main performance parameters of bellows which depends on the geometric dimensions, especially shell thickness of the bellows. U-shaped bellows,the most wildly used kind in engineering is commonly hydraulic pressure formed, and the deformation in board-ring is much greater than that in shell-ring. Considering that shell thickness is decreasing with increase of its radius in forming process. ,the thickness variation with redius can be described by a power function which is used to modify the commonly used empirical formula for axial stiffness calculation. Through comparison of the computational results by FEM simulation using MSC Nastran and the results by experiments the effectiveness of the method presented in this paper is verified. Related Articles | Metrics

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Static and Dynamic Characteristic Analysis and Structure Optimization of Hanger Isolator of Exhaust System QIAN Sheng，LU Yi-min 2012, 32(5): 193-197.  DOI: 10.3969/j.issn.1006-1335.2012.05.044 Abstract ( )   Hanger isolators are the critical components of automobile exhaust system, and its static and dynamic elastic characteristics affect directly performance of vibration isolation. The static and dynamic elastic characteristics of a typical hanger isolator was investigated by using nonlinear Finite Element Method. Finite element model of the hanger isolator was established first, then suitable constitutive equations selected, static and dynamic elastic characteristics simulated and static stiffness of the hanger isolator in calculated. Under the sinusoidal excitation at different frequency the dynamic stiffness and damping angle were calculated by cross-power spectrum through dynamic simulation. Finally, the structure of the hanger isolator was optimized by orthogonal experiment to enhance performance of the isolator. Related Articles | Metrics

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Measurement and Analysis of the Dynamic Modulus of Polymer Materials Based on Fractional Model HAN Bao-kun,ZHANG Ting-ting, CAO Shu-ming 2012, 32(5): 198-202.  DOI: 10.3969/j.issn.1006-1335.2012.05.045 Abstract ( )   The Polymer damping material with good structure damping characteristics plays a significant role in vibration and noise reduction. The dynamic modulus of viscoelastic material is usually characterized by its complex modulus which is of nonlinear behavior of variation with system frequency and environment temperature. The dynamic experiment of one polymer on test machine has been carried out. And the data of test have been fitted by fractional Kelvin model respectively. It is shown by experimental results that the  fractional Maxwell model could be used to simulate accurately the curve of variation of storage modulus and dissipation modulus of polymer with frequency. And this model is not only simple in form but also needs fewer parameters for calculation. The results offer a reference for practical application. Related Articles | Metrics