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18 April 2010, Volume 30 Issue 2 Previous Issue    Next Issue
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目录
论文
振动理论与数值解法
运载工具振动与噪声
建筑振动与建筑声学
信号处理与故障诊断
减振降噪设备和器材
标准规范与评价
振动噪声测试技术


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《CONTENTS》 2010, 30(2): 0-1.  Abstract ( )   PDF (2965KB) ( )   Related Articles | Metrics

论文

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《Review of State of The Art of Particle Filtering Technique》 ZHANG Rui-hua;LEI Min 2010, 30(2): 1-4.  DOI: 10.3969/j.issn.1006-1355.2010.02.001 Abstract ( )   PDF (1734KB) ( )   This paper reviews the state of the art of particle filtering technique. The novel methods for particle filtering calculation of four kinds of particles are introduced. The problems in target tracking, navigation and orientation are summarized. At last, the further study and practical applications of particle filtering technique are prospected. Related Articles | Metrics

振动理论与数值解法

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《Analysis of Transmission Paths of Ship Stern VibrationBased on Power Flow Theory》 FENG Guo-ping;HUANG Xiu-chang;LIU Xing-tian;ZHANG Zhi-yi;HUA Hong-xing 2010, 30(2): 5-8.  DOI: 10.3969/j.issn.1006-1355.2010.02.005 Abstract ( )   PDF (1274KB) ( )   Vibration of ship sterns is a key point in ship vibration control. Study of the characteristic of vibration transmission paths of ship stern will be helpful for vibration reduction of the ship stern. Based on the modal shape analysis methods and power flow theory, the transmission path of the stern system vibration is deducted and analyzed numerically. The results show that the stern bearing is the main path for lower frequency vibration, while the thrust bearing base is the main path for medium frequency vibration. Related Articles | Metrics

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《Influence of Mechanical Filter with Periodic Structure on Vibration Transmission Properties of Raft Isolation System》 HUANG Xiu-chang;FENG Guo-ping;ZHANG Zhi-yi;HUA Hong-Xing 2010, 30(2): 9-12.  DOI: 10.3969/j.issn.1006-1355.2010.02.009 Abstract ( )   PDF (1284KB) ( )   A medium with periodic heterogeneity has special frequency ranges in which waves may be either effectively attenuated or allowed to propagate in space. These frequency ranges are referred to as stop bands (or band gaps) and pass bands (or bands). Such unique characteristics can be employed to design a kind of virtual mechanical filters with periodic structures. The mechanical filter can be inserted between the lower isolator and the base of the raft isolation system to alter the transmission properties from the machine to the base, so that the frequency of the raft isolation system can approach its excitation frequency, and differ from the shells intrinsic frequency and excitation frequency of the cabin. The transmission matrix method is used to analyze the transmission property and the dynamic response of the raft system. Result shows that the responses of displacement, force and power flow of the base can be greatly reduced when the excitation frequency is within the stop bend of the periodic structure. Related Articles | Metrics

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《Numerical Simulation and Optimization of Doublestage Wire Rope Vibration Absorber for Stretchersupport on Emergency Ambulance》 XU Xin-xi;WANG Meng;NING Jie;TAN Shu-lin;GAO Zhen-hai 2010, 30(2): 13-15.  DOI: 10.3969/j.issn.1006-1355.2010.02.013 Abstract ( )   PDF (1012KB) ( )   In this paper, four design schemes of vibration absorber are proposed for the stretchersupport system on emergency ambulance. In these schemes, doublestage wire rope vibration absorber with long and short springs, cylindershaped damper and elastic limiter devices are employed. The virtual prototype model of nine DOFs is built for dynamic simulation using ADAMS code, including four wheels, vehicles body, equivalent suspension, stretchersupport system and the mass of supine body. The simulation model is excited in the time domain by acceleration signals on the axletrees end from the road test. The best scheme is selected after simulation and optimization, its vibration absorbing efficiency can reach 31.29% and meet the requirements of application. Related Articles | Metrics

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《Simulation Study on Active Control Method of Flexible Coupled Isolation System》 XU Yang;MENG Zhuo;SUN Yi-ze;HUA Hong-xing 2010, 30(2): 16-18.  DOI: 10.3969/j.issn.1006-1355.2010.02.016 Abstract ( )   PDF (824KB) ( )   A new method, which combines impedancemobility modeling method with matrix transmission modeling method, is presented for the study of activeflexible coupled isolation system. The mathematical model of flexible coupled isolation system is constructed, including isolated equipment, electromagnetic activepassive isolator, and flexible base. The linear quadratic Gaussian method (LQG) is applied to design the active controller of the isolation system. Simulation results show that this control method is effective. Related Articles | Metrics

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《Nonlinear Timevarying System Identification Based on NARMA Model with Improved Recursive Least Square Scheme》 PENG Hai-bo;YU Kai-ping;LIU Wei 2010, 30(2): 19-22.  DOI: 10.3969/j.issn.1006-1355.2010.02.019 Abstract ( )   PDF (1347KB) ( )   Using the timevarying NARMA (Nonlinear Auto Regressive Moving Average) model and the improved recursive least square algorithm, an identification method for nonlinear timevarying structure system is proposed. Firstly, the dynamic model of the timeindependent structure system is changed to an autoregressivemovingaverage model by means of linear transform method. Then the nonlinear function of this model is expanded to a polynomial about input and output using Taylor expansion, and the polynomial timevarying NARMA model, which is a linear combination of parameters, is obtained. Using the basic sequences to fit the timevarying parameters of the model, the nonlinear timevarying system is then transformed into a linear timeinvariant system, whose parameters can be estimated by improved recursive least square algorithm. Finally, the proposed method is validated by the simulation of a 3DOF structural system with nonlinear timevarying stiffness. Related Articles | Metrics

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《Nonlinear Dynamic Modeling and Analysis of Cable in Boom Shipmounted Crane》 WANG Gan-cheng;JIN Chang-ming;CHEN Yun-wen;ZHANG Jin;LI Hong-guang 2010, 30(2): 23-25.  DOI: 10.3969/j.issn.1006-1355.2010.02.023 Abstract ( )   PDF (883KB) ( )   A traditional lumpedmass model for the boom shipmounted crane is established in this paper. The nonlinear dynamic equation is presented using the EulerLagrange method. Then the nonlinear dynamic behavior of the cable is analyzed numerically, and the impact of some key parameters on the cargo pendulum is studied. Results of this study are of significance for the operation of shipmounted cranes. Related Articles | Metrics

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《Vibration Analysis of a Tennis Racket with TMD》 ZHUANG Biao-zhong;YING Zu-guang;DIAO Yi-ping 2010, 30(2): 26-29.  DOI: 10.3969/j.issn.1006-1355.2010.02.026 Abstract ( )   PDF (572KB) ( )   The TunedMassDamper (TMD) technique, presented in Literature ［1］, is based on the vibration absorption principle. In recent three decades, it has been applied to many fields such as structure and bridge engineering for mitigating vibration excited by wind and earthquake［2］. Recently, The TMD has been applied to tennis rackets for vibration control. In the present paper, the free vibration of a tennis racket is tested and then the first natural frequency is obtained by the powerspectraldensity analysis. The results are verified by the analysis of transfer function and correlation function. On the other hand, the equation of motion of a massstring as a simplified model of tennis racket with TMD is given, and its natural frequency is obtained. Related Articles | Metrics

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《Damping Analysis for Screws Vibration System of Hydraulic Vibration Injection Molding Machine in Plasticizing Process》 WANG Quan;QU Jin-ping 2010, 30(2): 30-33.  DOI: 10.3969/j.issn.1006-1355.2010.02.030 Abstract ( )   PDF (1268KB) ( )   The vibration amplitude of novel hydraulic vibration injection molding machine is greatly influenced by the polymer fusible damping in plasticizing process. Based on the shear theory of hydrodynamics, the damping coefficient in plasticizing process is determined in this paper. The results show that the damping of the vibration system is not only related to the geometrical parameters of the screw and property of the material, but also the molding technological parameter, such as vibration intensity, screws rotation speed, etc. And the most remarkable affect to the damping is the screws rotation speed. Related Articles | Metrics

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《Estimates of Vibration Isolation Efficiency for Floating Raft Isolation System by Statistical Energy Analyzing Method》 LIU Rui-feng;WANG Qiang;ZHANG Yi;GUO Yun-song 2010, 30(2): 34-37.  DOI: 10.3969/j.issn.1006-1355.2010.02.034 Abstract ( )   PDF (1272KB) ( )   Using the statistical energy analyzing method (SEA), a model for analyzing the marine floating raft isolation system is established. The vibration isolating effect of the raft isolation system is measured and analyzed by means of the Vibration Level Difference method. Comparing experiment result with theoretically estimated value is civen out. It shows that this method can meet general need of engineering design. Related Articles | Metrics

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《Fuzzy Logic Control of DoubleStage Vibration Isolation System》 HE Xiao-guang 2010, 30(2): 38-42.  DOI: 10.3969/j.issn.1006-1355.2010.02.038 Abstract ( )   PDF (1599KB) ( )   The fuzzy active vibration control technique is studied in this paper. In this technique, it is not necessary to account for the feedback of minor vibration sources to the controllers input (coupling channel) induced by the adaptive control process and the influence of the transmission function between the minor vibration sources and the errorevaluation sensors (error channel) on the control procedure. Thus, the control system becomes simpler and more feasible. Simulation result verifies that this strategy is effective for periodic and random vibration signals. Related Articles | Metrics

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《Simulation of Nonlinear Vibration System Based on Simulink》 LU Chun-hong;BAI Hong-bai;HAN Feng-qi;MENG Qiu-hong 2010, 30(2): 43-44.  DOI: 10.3969/j.issn.1006-1355.2010.02.043 Abstract ( )   PDF (637KB) ( )   Based on Simulink software, the simulation model of a nonlinear vibration system with bilinear restoring force is established and analyzed. The result shows that Simulink software can simplify computer processing and raise the reliability of computation. The displacement, speed and acceleration responses in the time domain can be gained more easily. Related Articles | Metrics

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《Study on the Impact of Shock Absorber on Vibration and Noise of Airconditioners Outdoor Unit》 LI Bao-ze;FAN Ying-tao 2010, 30(2): 45-49.  DOI: 10.3969/j.issn.1006-1355.2010.02.045 Abstract ( )   PDF (1840KB) ( )   The Dynamic analysis models of the airconditioner outdoor unit and the compressor refrigeration system are established by means of the finite element method (FEM). The modal analysis is carried out by ANSYS code. The impact of the piping on the compressors structural vibration using the rubber pads with different hardness is obtained. The natural frequency and vibration mode of the system are computed. Then the most suitable stiffness of the rubber pads can be used to reduce the compressors structural vibration. The vibration and noise of the pads with various stiffness are measured. The vibration velocity curves are plotted and the spectrum analysis is carried out. With the appropriate measures for forecasting the vibration and noise reduction, the design scheme may be more scientific, feasible and economic. Related Articles | Metrics

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《Theoretical Analysis and ANSYS Calculation of Longitudinal Vibration of Drill String》 XU Tao-yuan;ZHANG Qiang;CHEN Can;SHEN Xi;ZHENG Wei 2010, 30(2): 50-53.  DOI: 10.3969/j.issn.1006-1355.2010.02.050 Abstract ( )   PDF (1316KB) ( )   Drill string vibration is the main reason for its failure and fatigue damage. Employing the dynamics theory and its basic differential equations with a reasonable assumption, the longitudinal vibration model of the drill string is established and analyzed by means of ANSYS code. The rule of the drill string vibration is obtained. Results of this work may provide some guidance for design and operation of the drill string. Related Articles | Metrics

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《Application of Similarity Theory in Simulation Analysis of Semiactive Suspension》 DAI Fang;WANG Hong-xing 2010, 30(2): 54-56.  DOI: 10.3969/j.issn.1006-1355.2010.02.054 Abstract ( )   PDF (896KB) ( )   An adjustable damper and its working principle are introduced, and its mechanical model is established. Using vehicles dynamics theory, a dynamic model of a quarter of semiactive suspension is established. The similarity theory is introduced and applied in simulation analysis of the semiactive suspension. A similarity circuit of a quarter of the semiactive suspension is established. Through the simulation of the similarity circuit, the effect of semiactive suspension on improving vehicles ride comfortableness is forecasted. Related Articles | Metrics

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《Analysis and Testing of Axial Load Effects on Ball Screws Friction Torque Fluctuations》 KANG Xian-min;;FU Wei-ping;WANG Da-cheng;LI Ting;WANG Shi-jun 2010, 30(2): 57-61.  DOI: 10.3969/j.issn.1006-1355.2010.02.057 Abstract ( )   PDF (1820KB) ( )   Based on the Hertz contact theory, the relation between preload force as well as axial load and contact rigidity is studied. An approach for analyzing the influence of the resistance effects on ball screws friction torque fluctuation, when the balls are pushed into the raceway, is put forward, and the influencing parameters for friction torque fluctuation under axial load are obtained. The tests of ball screw systems friction torque under axial load indicates that preload force is the main factor to influence the screws friction torque fluctuation, and the axial load also raise the friction torques fluctuation. Related Articles | Metrics

运载工具振动与噪声

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《Study on Characteristics of Interior Noise of Urban Railway Passenger Vehicle》 HUANG Jie;CUI Hong-fei;YIN Xue-wen 2010, 30(2): 62-65.  DOI: 10.3969/j.issn.1006-1355.2010.02.062 Abstract ( )   PDF (1407KB) ( )   In this paper, the interior noise characteristics of an urban rail passenger vehicle traveling at rated velocity are studied by using the combination of finite element method and boundary element method. The structural excitation forces acting on the vehicles body are described by the load spectra at the vehicles bottom frame. The body surfaces vibration velocities are calculated by means of finite element method, while the interior noise field is predicted by using boundary element method. Finally, the contributions of the different portions of the bodys surfaces to the maximum SPL field points are analyzed, and their features versus frequency and space are also analyzed. Related Articles | Metrics

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《Method of Noise Prediction and Measures of Noise Reducing in Highway Tunnel》 SHI Li-ming 2010, 30(2): 66-68.  DOI: 10.3969/j.issn.1006-1355.2010.02.066 Abstract ( )   PDF (983KB) ( )   A method of noise prediction and the measures of noise reducing in highway tunnel is studied with an expressway tunnel as an engineering background. The prediction model, the methods of determination of the parameters, and an example for computation are given. Several measures for noise reduction are compared. Related Articles | Metrics

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《Characteristics of Noise in Subway Cars》 ZHANG Xiao-pai;LIU Yan;ZHONG Zhi-fang 2010, 30(2): 69-71.  DOI: 10.3969/j.issn.1006-1355.2010.02.069 Abstract ( )   PDF (988KB) ( )   The noise experiments in a subway car were made. The measurement points were positioned at the centre of the cars body, and at the vestibule diaphragm and the bogie, respectively, above the floor with different heights. It is found that the noise at the airoutlet is 77.8 dB(A) in the case of static car. When the train was running, however, the noise of the subway car is 1.0-5.9 dB(A)　higher in the subway tunnel than that in the railway viaduct. Wheel/rail noise is the major contributor to the internal noise, while the noise from auxiliary equipments can usually be neglected in the measurement except the portions near the airoutlet in the running car. The coach airproof affects the noise distribution in the car, so the airproof of the door and the vestibule diaphragm should be improved. Related Articles | Metrics

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《Vibrations of Complex Structure Induced by High Speed Trains》 DENG Shi-hai;GUO Xiang-rong;WANG Hui-hui;GUO Zhan-yuan 2010, 30(2): 72-76.  DOI: 10.3969/j.issn.1006-1355.2010.02.072 Abstract ( )   PDF (1738KB) ( )   Aiming at new Guangzhou station on WuhanGuangzhou passenger line, the trainbridge submodel and the bridgestation submodel are established. Through the analysis and calculation of train and bridge dynamic interaction, the load histories of the nodes of the trackbeam are obtained. Then, taking the load histories as the external excitation acting on the bridgestation submodel, the transient analysis is carried out, and the vibrations of waiting rooms floor are calculated and discussed. Finally, results are compared with specifications of allowable vibration levels. The influence of running train on safety of waiting rooms floor is discussed. Related Articles | Metrics

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《Rational Shafting Alignment of Vessels and Analyses of Influencing Parameters》 ZHONG Tao;GENG Hou-cai;RAO Zhu-shi;WANG Xi-ding 2010, 30(2): 77-79.  DOI: 10.3969/j.issn.1006-1355.2010.02.077 Abstract ( )   PDF (935KB) ( )   A rational shafting alignment for a real vessel is carried out. The rigidity of bearing support and vessel deflections are taken into consideration. Their influences on the results of shafting alignments are analyzed to provide a deeper comprehension and theoretical reference for vessel designers. Related Articles | Metrics

建筑振动与建筑声学

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《Study on Comfortableness of a Gymnasium under the Condition of Floor Vibration》 XIE Wei-ping;HONG Wen-lin;LI Ting 2010, 30(2): 80-83.  DOI: 10.3969/j.issn.1006-1355.2010.02.080 Abstract ( )   PDF (1336KB) ( )   With the development of largespan, lighter and more flexible modern structures, much attention has been paid to the issues of structure vibration and structural comfortableness in vibration environment caused by human activities. Yet there is hardly a unified standard available for evaluation of the structural comfortableness. The issue of the structural comfortableness of a gymnasium under the condition of floor vibration is discussed in the paper. The computation model of a finite large floor is established and its natural frequencies under different boundary conditions and loading conditions are calculated. The natural frequencies and vibration accelerations of the floor under the most unfavorable conditions are measured. The computation result of floors natural frequencies is in consistent with that of site measurement. Thus, the rationality of the numerical calculation model is verified. Based on the measured acceleration values, comfortableness in the floor vibration environment is evaluated by using the international standard ISO 26311997. The evaluation results show that the floor can satisfy the demand of comfort. The method for comfortableness evaluation used in this paper can provide a reference for other engineering structures. Related Articles | Metrics

信号处理与故障诊断

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《Analysis of Stall Vibration Mechanism of Centrifugal Compressor and its Improvement》 Chen Hong-wei 2010, 30(2): 84-87.  DOI: 10.3969/j.issn.1006-1355.2010.02.084 Abstract ( )   PDF (1606KB) ( )   The mechanism of rotation stall of compressors produced by a factory in Longyan of Fujian province is analyzed. It is found that the air flow impacts the working surface of the blade when the wind flow reduces, while many air vortexes occur in the back surface of the blade. Thus, the net sectional area of the air flow decreases. The air bubbles induced by the vortexes translate in the sense opposite to the rotation of the impeller and cause the vibration. Summing up the type and characteristics of the rotation stall of the compressor, a method for monitoring the rotation stall signal is put forward based on Fast Fourier Transform. With this method, the omen of rotation stall can be found. With spectrum analysis, some improvement measures are proposed. This method has been proved simple, convenient and practical in recent oneyear application. Related Articles | Metrics

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《Breathing Characteristics of the Crack in a Rotating Shaft when Rotor Passing through Critical Speed》 LI Ning;CHENG Li;;CHEN Xue-feng 2010, 30(2): 88-91.  DOI: 10.3969/j.issn.1006-1355.2010.02.088 Abstract ( )   PDF (1383KB) ( )   Based on the dynamic equations of cracked rotor under constant speed, the general dynamic equations of a Jeffcott rotor with a transverse crack are developed for studying the influence of nonlinear breathing behavior of the crack due to whirling on the critical speed of the rotor. The vibration response of the cracked rotor, when the rotor is accelerating and passing through critical speed, is investigated by numerical method. The results reveal that the imbalance orientation angle has a greater influence on the critical speed, the crack breathing behavior is weakened near the critical speed, and the maximum response of the cracked rotor during constant accelerating process is fall behind the rotation of the center of gravity. The experiment of passing through critical speed of a cracked rotor was made on a rotor testing platform. And the experimental observations support the analytical results. Related Articles | Metrics

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《Analysis of Engine Vibration and Partialabrade Fault and Method for Solving the Issues》 LIN Hai-ying;WANG Jing-ran 2010, 30(2): 92-95.  DOI: 10.3969/j.issn.1006-1355.2010.02.092 Abstract ( )   PDF (1409KB) ( )   Engine failuremode vibration and partial abrade are the most bothersome problems for engine enterprises. In this paper, some helpful experiences for solving these issues are summarized for an engine. Combining the experiences with theoretical analysis, the efficient method on process of design, fabrication and test is provided. Related Articles | Metrics

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《Highfrequency Load Identification of Complex Structural Coupling System》 XUE Yong-gang;XIE Shi-lin;ZHANG Xi-nong 2010, 30(2): 96-98.  DOI: 10.3969/j.issn.1006-1355.2010.02.096 Abstract ( )   PDF (898KB) ( )   The paper investigates the load identification of a threeplate coupling system based on the statistical energy analysis theory. Firstly, the stable power injection method is employed to identify the inner loss factors and the coupling loss factors of substructures, in which the indirect coupling characteristics are considered. Based on the established power flow balance equation of the system, the identification of concentrated load is conducted. The results show that, in the highfrequency range, the identified input power agrees well with the measured input power. The work presented in the paper provides a theoretical reference for load identification of structures in the high frequency domain. Related Articles | Metrics

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《Damage Detection of Shallowly Buried Civil Airdefense Engineering Structures》 YAN Xiang-cheng;XU Jin-yu;ZHENG Fei 2010, 30(2): 99-102.  DOI: 10.3969/j.issn.1006-1355.2010.02.099 Abstract ( )   PDF (1340KB) ( )   With the development of civil airdefense engineering structures, their damage diagnosis and safety evaluation have become important problems needed to be solved urgently. A new method to detect the damage of the shallowly buried civil airdefense engineering structures is proposed in this paper. In this method, the sum of absolute values of the variation rates of the first three modes is selected as a parameter for damage detection. An actual civil airdefense engineering structure is employed as an example. It is shown that this parameter for damage detection is not only sensitive to the location and extent of the damage, but also obeys the superposition law when there are two damages. Thus, damage detection of the civil airdefense engineering structures becomes convenient. Related Articles | Metrics

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《Application of EEMD to Suppression of Mode Mixing in Oscillation Signals》 QI Tian;QIU Yan;WU Ya-feng 2010, 30(2): 103-106.  DOI: 10.3969/j.issn.1006-1355.2010.02.103 Abstract ( )   PDF (1492KB) ( )   Mode mixing is one of the drawbacks in empirical mode decomposition (EMD). It makes the IMF component to lose its original physical meaning. Ensemble empirical mode decomposition (EEMD) is a new method which applies the noise assisted data analysis to EMD. It can improve the EMD decomposition and suppress mode mixing phenomena. Application of EEMD in suppression of mode mixing for mode extraction from oscillation signals has made a better result for engineering projects. Related Articles | Metrics

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《Application of Pattern Filter Method on Well Sites Vibration Signal Separation》 LU Miao-rong;WANG Qian 2010, 30(2): 107-110.  DOI: 10.3969/j.issn.1006-1355.2010.02.107 Abstract ( )   PDF (1348KB) ( )   A new approach—pattern filter method（PFM）is used to study the application of the drilling signal separation on well site. When drilling is on with tricone or PDC bit, the vibration signals of the drilling pump and the top of the drill string are obtained. Such a signal separation method has a good prospect for engineering signal processing. Related Articles | Metrics

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《Fault Diagnosis of Machines Based on Improvement of Grey Incidence》 WANG Qi-zhi;WANG Xiao-xia 2010, 30(2): 111-113.  DOI: 10.3969/j.issn.1006-1355.2010.02.111 Abstract ( )   PDF (883KB) ( )   Because of the complex nonlinear relation between fault sign and fault type, the traditional methods can not exactly meet the need of engineering application. In this paper, a method of generalized grey incidence of area is proposed for analysis of the comparability and the proximity of sequences. With this method, the type of faults of refrigeration compressors may be diagnosed effectively. Related Articles | Metrics

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《Application of Wavelet Packet Analysis in Fault Diagnosis of Rotor Bars Breaking of Motors》 LI Tao;WANG Xin 2010, 30(2): 114-117.  DOI: 10.3969/j.issn.1006-1355.2010.02.114 Abstract ( )   PDF (1185KB) ( )   The common faults of squirrelcage induction motor and the importance of fault diagnosis are introduced. The electrical and mechanical features of signals are extracted by the modified wavelet packet algorithm. A fault diagnosis method based on wavelet packet analysis of frequencyband energy is proposed. The experiment shows that with this method all the broken bars faults of the rotor can be detected rapidly with high accuracy. This method has high feasibility and extensive applicability. Related Articles | Metrics

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《Modified Method for Wavelet Denoise Threshold Selection and its Application in Health Monitoring》 CHENG Shuai;ZHANG Bo;WANG Xiao-qing 2010, 30(2): 118-120.  DOI: 10.3969/j.issn.1006-1355.2010.02.118 Abstract ( )   PDF (965KB) ( )   A novel threshold function is constructed based on the wavelet threshold denoising method presented by D.L. Donoho and I.M. Johnstone. This new threshold function has many advantages over the traditional soft/hard threshold functions. It is simple in expression, as continuous as the softthreshold function, and highorder differentiable. Thus, it is convenient for mathematical processing. This new threshold function also overcomes the shortcoming that there is an invariable difference between the estimated wavelet coefficients and the decomposed wavelet coefficients in the soft threshold function. Meanwhile, the new threshold function is more flexible than the soft/hardthreshold function. All these advantages make it possible to construct an adaptive denoising algorithm. Simulation results indicate that the new denoising method adopting the new threshold function can suppress the PseudoGibbs phenomena near the singularities of the signal effectively. And the numerical results also show that the new method gives better MSE performance and SNR gains than the traditional hard/softthreshold methods. This method is applied to the vibration signal denoising of a bridge, and the result shows that it can eliminate the noise effectively. Related Articles | Metrics

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《Improved Wavelet Threshold Denoising Method and Its Simulation Using MATLAB》 LI Shu-yu 2010, 30(2): 121-124.  DOI: 10.3969/j.issn.1006-1355.2010.02.121 Abstract ( )   PDF (1355KB) ( )   In this paper, several wavelet denoising methods are compared and analyzed. On these bases, a new threshold function is constructed. The improvement of threshold selecting is made. Simulation experiment of signal denoising is carried out using MATLAB software. The advantage of improved wavelet denoising method is demonstrated, and better denoising effect is gained. Related Articles | Metrics

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《Bearings Fault Detection Method Based on Signal Wavelet Singularity Analysis》 WANG Hong-wei 2010, 30(2): 125-129.  DOI: 10.3969/j.issn.1006-1355.2010.02.125 Abstract ( )   PDF (1880KB) ( )   Aiming at the disadvantage that the wavelet singularpoint detection based method is more sensitive to the noise in bearings vibration signal identification, the scheme of bearings fault detection is proposed based on the number of singularity points using wavelet transform modulus maximum with constant length. In the test, the wavelet transform modulus maximums of fractal spectrum, fractal spectrum entropy, Lipschitz spectrum, and Lipschitz spectrum entropy are analyzed and compared. The testing results show that the number of singularity points with constant length can effectively reflect the characteristics of bearings faults. The proposed method is compared with the method based on wavelet packet energy spectrum and wavelet singularpoint detection based method in the experiments. The results show that the number of singularity points using wavelet transform modulus maximum with the constant length is particularly well adapted to describe fault characteristics and fault diagnosis, which outperforms the method based on wavelet packet energy spectrum in the aspects of detection time and detection rates. Related Articles | Metrics

减振降噪设备和器材

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《Design of Piezoelectric Transducer for Middle Ear Implant Based on Coupling Model》 LIU Hou-guang;MING Xiao-feng;TA Na;RAO Zhu-shi 2010, 30(2): 130-133.  DOI: 10.3969/j.issn.1006-1355.2010.02.130 Abstract ( )   PDF (1433KB) ( )   To design a simplefloating mass type piezoelectric transducer, consisting of a piezoelectric stack, a metal case and a clamp, for middle ear implant, a biomechanics model coupled by human middle ear and piezoelectric transducer is constructed. This model is built based on a complete set of computerized tomography section images of a healthy volunteers left ear by reverse forming technology. The validity of this model is confirmed by comparing the result of motion of the stapes of this model with the published experimental data on human temporal bones. It is shown that the designed transducer can be implanted on the incus long process by a simple surgical operation, and the stapes footplate displacement by its excitation at 10.5 Vrms is equivalent to that from acoustic stimulation at 100 dB SPL, which is adequate stimulation to the ossicular chain. Related Articles | Metrics

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《Experimental Study on Vibration and Noise of Steelfree Fiber Reinforced Frictional Material》 MENG Chun-ling;ZHANG Yuan;YANG Sheng;TIAN Zheng-bing 2010, 30(2): 134-137.  DOI: 10.3969/j.issn.1006-1355.2010.02.134 Abstract ( )   PDF (1382KB) ( )   By means of vibration and noise experiments for a pad made of steelfree fiber reinforced frictional material, the damping coefficient and other factors, which impact the vibration and noise of the pad induced by braking, are studied in both frequency domain and time domain. Through the comparative analysis of vibration and the noise signals, the relationship of vibration and noise is investigated. In addition, the mechanism of vibration and noise of the brake pad is discussed. Some effective control approaches are suggested. The results may provide some references for further study on this material for vibration and noise reduction. Related Articles | Metrics

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《Modal Testing and Analysis of Vibration Reduction Behavior of Metalplastic Compound Materials》 LUO Zhi-gao;CHEN Bao-lei;PANG Chao-li 2010, 30(2): 138-141.  DOI: 10.3969/j.issn.1006-1355.2010.02.138 Abstract ( )   PDF (1296KB) ( )   In order to satisfy the requirement of damping material in industry, a kind of metalplastic compound material made of 45# steel and PA66 nylon is fabricated. Modal test is carried out for this kind of material. The frequency response and damping ratio of the compound material in forced vibration are tested. Its damping behavior is analyzed. The results show that under the same order of vibration mode, the amplitude of compound materials is 17%～28% lower than that of the comparative material, the natural frequency of the compound materials decreases rapidly, and the damping ratio increases obviously. Thus, the damping effect of compound materials is improved greatly. Related Articles | Metrics

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《Investigation on Electromagnetic Coils of Multistage Pistontype MR Damper》 WANG Yu-fei;SHU Li-hong;HE Lin 2010, 30(2): 142-145.  DOI: 10.3969/j.issn.1006-1355.2010.02.142 Abstract ( )   PDF (1446KB) ( )   In this paper, the advantages of multistage pistontype MR damper are analyzed. The characteristics of the electromagnetic coils are systematically investigated. The simulation model for the MR damper is established and analyzed by means of the finite element software of Maxwell. From the model analysis, it is shown that to raise the utilization rate of the magnetic circuit, the electromagnetic coils in the damper should be connected in parallel form and conducted with inverse current. In order to improve the distribution of magnetic flux and guarantee the uniform distribution of magnetic induction in the dampers gap, the effective length in the magnetic circuit should be adjusted and trapezoidal shaped section for the piston alveolar should be adopted. Related Articles | Metrics

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《Improvement of Sound Absorption Characteristics for Thick Microperforated Panels Using Thin Stainlesssteel Fibers》 XU Ying;HE Liyan;CHEN Ting;LI Chen-xi 2010, 30(2): 146-148.  DOI: 10.3969/j.issn.1006-1355.2010.02.146 Abstract ( )   PDF (1062KB) ( )   Thick microperforated panels (MPP) usually do not have such a good sound absorption feature as the thin panels do because of their high resistance and/or reactance. In order to improve the thick MPPs acoustical performance, thin stainlesssteel fibers are inserted into the orifices of the thick MPP, and their sound absorption coefficients are measured. Results show that the thin stainlesssteel fibers can widen the frequency band for sound absorption of the thick MPP effectively. When the insertion rate of the fibers reaches 50% and the usage of fibers reaches 0.75mg per orifice, the frequency band of sound absorption is 3921168Hz for the absorption coefficient larger than 0.5. While for the MPP without fiber insertion the frequency band for sound absorption is only 5301076Hz. Related Articles | Metrics

标准规范与评价

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《Evaluation Method of Human Body Response to Vibration》 ZHANG Zhi-fei;XU Zhong-ming;HE Yan-song;WANG Xian-Guo;XIE De-yun 2010, 30(2): 149-155.  DOI: 10.3969/j.issn.1006-1355.2010.02.149 Abstract ( )   PDF (2647KB) ( )   Several international evaluation methods of vibration, ISO26311985, ISO26311997，BS68411987 and Absorbed Power, are introduced in detail, and their characters are summarized. The present status of research on evaluation methods of vibration is analyzed, and the present status of research on human response characteristics to vibration is summarized. It is shown that the human response to vibration is very complicated and influenced by human posture, human weight and vibration magnitude etc. So, searching for more suitable and scientific evaluation methods may become a hot research focus is the area of vibration evaluation. According to domestic research in this area, some suggestions are presented, such as updating the national standards, measuring the human response to vibration and carrying out fundamental research etc., in order to establish an evaluation method of vibration which is suitable to our Chinese. Related Articles | Metrics

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《Overview of Domestic and International Railway Noise Standards》 GONG Kai;LIU Lin-ya 2010, 30(2): 156-159.  DOI: 10.3969/j.issn.1006-1355.2010.02.156 Abstract ( )   PDF (1279KB) ( )   Traffic noise has become one of the major pollution sources in urban area. At present, countries all over the world are constantly updating their own standards of traffic noise in order to meet their own domestic requirements. In this paper, the railway noise standards of some major countries in the world are analyzed. It may provide some references and inspirations for working out our own railway noise standard. Related Articles | Metrics

振动噪声测试技术

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《Auditory Sensation Device for Sound Source Localization》 WANG Qing-sheng;TA Na;RAO Zhu-shi 2010, 30(2): 160-162.  DOI: 10.3969/j.issn.1006-1355.2010.02.160 Abstract ( )   PDF (878KB) ( )   In this paper, a new type of instrument is designed for the purpose of localizing the sound source. It is a relatively compact structure. This bionic structure is to mimic the localization function of the ears of the parasitoid fly Ormia ochracea. It consists of three elastic diaphragms, three bars which are connected to the diaphragms, and some other mechanical components. Analysis of this structures dynamic behavior shows that the incident angles of the sound have special relationship to the responses of this instrument, and the incident angles can be estimated by detecting the vibrations of the three elastic diaphragms. Related Articles | Metrics

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《Noise Forecast of Aircleaners with Random Transfer Function》 YUE Gui-ping;ZHANG Yi-min 2010, 30(2): 163-166.  DOI: 10.3969/j.issn.1006-1355.2010.02.163 Abstract ( )   PDF (1393KB) ( )   The method of noise analysis of aircleaners with random transfer function is presented using matrix perturbation theory, matrix calculus, Kronecker algebra and generalized second moment method. Considering the uncertainty factors of the atmosphere, the random response of the aircleaner is described clearly in the time and space domain, and the decibel (A) value of the former second moment of random response at the sound outlet of the aircleaner is obtained. Related Articles | Metrics

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《Identification and Design of Highlevel Acoustic Laboratory》 FU Qi;WEN Zhou-bin;LUO Wei;WANG Huan 2010, 30(2): 167-169.  DOI: 10.3969/j.issn.1006-1355.2010.02.167 Abstract ( )   PDF (947KB) ( )   Audio acoustics lab, including a fullanechoic chamber and a control room, is subsidiary to Zhejiang electroacoustic research and development center, CAS. The fullanechoic chamber，in the light of National Standards such as GB 68821986, JJF 11472006 and the corresponding international standard such as ISO37452003 etc, was designed by Institute of Acoustics, Chinese Academy of Sciences and BSWA Technology Co. Ltd. Shanghai Shengwang Acoustic Engineering Co. Ltd. was responsible for the internal acoustic decoration and the guidance of civil engineering construction of the laboratory. After the completion of laboratory, the lab passed the test and identification of the Chinese Institute of Metrology, and its respective indicators reached the design requirements. The design, construction overview and identification results of the laboratory are described in this paper in detail, which can be used as reference when it comes to similar laboratory. Related Articles | Metrics

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《Experimental Study on Acoustic Characteristics of Jet Flame with Twinfluid Airblast Atomizing Burner》 YAN Shi-sen;GUO Qing-hua;LIANG Qin-feng;YU Guang-suo 2010, 30(2): 170-174.  DOI: 10.3969/j.issn.1006-1355.2010.02.170 Abstract ( )   PDF (1783KB) ( )   The acoustic characteristics of jet flame with twinfluid airblast atomizing burner in different combustion conditions are studied. The experimental results show that the jet flames appear to have four stages: laminar flow, turbulence, violence and blowout flame, with the increase of oxidant flow rate. Laminar flame generates a lowpower noise. Turbulent flame is made up of two broadbands of noise. The noise power of the violent flame is much higher than that of the former two flames. The results show that the flame noise is the combination of the atomization noise and the combustion noise. The processing of flame acoustic signals can be used as a method to monitor the flame stability. Related Articles | Metrics