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18 August 2010, Volume 30 Issue 4 Previous Issue    Next Issue
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振动理论与数值解法
运载工具振动与噪声
环境振动与环境噪声
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
工程实践


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振动理论与数值解法

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《Study on Acoustic Characteristics of Underwater Coating Structure》 YAO Xiong-Liang;WANG Xian-zhong;PANG Fu-zhen;SUN Long-quan 2010, 30(4): 1-5.  DOI: 10.3969/j.issn.1006-1355.2010.04.001 Abstract ( )   PDF (1813KB) ( )   Based on waveguide theory, the absorption coefficient, reflective coefficient and transmission loss of underwater coating structure in different backing conditions and incidence angles are provided by the method of delaminate analysis. The Transmission losses for five typical incidence angles are calculated. The result shows that the sound insulation performance of the structure for vertical incidence is very poor. The transmission losses under three backing conditions are calculated also. The result shows that transmission loss of the underwater coating structure for water backing is negligible in the case of lowfrequency, while it increases rapidly in the case of medium and high frequencies. In the case of singlelayer shell backing, the shell itself dominates the sound absorption of low frequency, while the underwater multilayered structure becomes important gradually in sound absorption for medium and high frequencies. In the case of doublelayer shell backing, the frequency response curve of transmission loss includes a resonance value, which deteriorates the acoustic characteristic of the underwater coating structure. Generally speaking, the sound insulation performance for laying nonhomogeneous compound structures is much better than that for laying homogeneous compound structures. Related Articles | Metrics

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《Study on Noise Radiation Characters of a Gearbox Housing under the Action of FluidStructure Coupling》 CHEN Fu-zhong;XIANG Chang-le;LIU Hui 2010, 30(4): 6-9.  DOI: 10.3969/j.issn.1006-1355.2010.04.002 Abstract ( )   PDF (1411KB) ( )   The finite element model of complex gearbox housing, with some lubricant in it, is built. The fluidstructure coupling theory is employed. On the base of vibration analysis, the exterior sound field is calculated with the acoustic boundary element theory. Then the noise radiation characters and the influences of the lubricant on the housing are obtained. Finally, the simulation results are verified by measuring the sound power levels of noise sources by means of sound intensity method. Related Articles | Metrics

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《Research on UltraLowFrequency Nonlinear Vibration Isolation System》 LU Chun-hong;BAI Hong-bai;YANG Jian-chun;LI Zhi-zun 2010, 30(4): 10-12.  DOI: 10.3969/j.issn.1006-1355.2010.04.003 Abstract ( )   PDF (967KB) ( )   Based on the analysis of vibration isolation mechanism of parallel combination of positive and negative stiffness, a new type of ultralowfrequency vertical vibration isolation system is developed in this paper. In this system, the parallel connection of springs with, respectively, positive stiffness and negative stiffness is applied so that it possesses high supporting stiffness as well as ultralow kinematic stiffness. And the stiffness of the system is also nonlinear. This method has solved the problem of ultralow frequency vibration isolation in the traditional passive vibration isolator system. Through the analysis of mechanical characteristic of this system, expression of the stiffness of the isolator and zero stiffness condition of the system at the equilibrium position are deduced. This method offers a theoretical guidance for the design of new type of nonlinear ultralowfrequency vibration isolators. Related Articles | Metrics

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《Analysis of Resonance of Superharmonic Wave of Order 3 for Suspended Cable under a Concentrated Load》 DENG Rui-ji;CHEN Zi-li;SHI Li-qun 2010, 30(4): 13-17.  DOI: 10.3969/j.issn.1006-1355.2010.04.004 Abstract ( )   PDF (1429KB) ( )   The possible hyperesonance phenomenon of suspended cable system is analyzed for two cases of forced vibration. The general expression of solution for hyperesonance of suspended cable is obtained. Using this general expression, the possibility and condition for appearance of hyperesonance of the system can be directly analyzed. Finally, the bifurcation diagrams of the third order superharmonic resonance of the firstorder modal of the system are provided. Related Articles | Metrics

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《Simulation of Active Noise Control of Engine Exhaust Based on LMS Algorithm》 ZHANG Xiang;LU Sen-lin 2010, 30(4): 18-21.  DOI: 10.3969/j.issn.1006-1355.2010.04.005 Abstract ( )   PDF (1421KB) ( )   There are various active noise control algorithms for engine exhaust noise simulation. However, their control effects are different due to the different complexities. To find out a more effective control algorithm, a simulink model for simulation of noise control of an engine exhaust is established using MATLAB code, and the simulation is done based on the LMS algorithm. From the simulation, the limitation of the LMS algorithm is evaluated in the case that the error acoustic path exists, and the LMS algorithm is improved for better control effect. Related Articles | Metrics

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《A Method for Analyzing Stability and NonLinear Behavior of NonLinear Dynamic Systems》 ZHOU Ming-gang;CHEN Yuan;HUANG Tao;ZHOU Jing-dong 2010, 30(4): 22-24.  DOI: 10.3969/j.issn.1006-1355.2010.04.006 Abstract ( )   PDF (940KB) ( )   In the nonlinear dynamic system, analyzing the influence of the system parameters on the stability and the amplitude of vibration under instable condition of the system is an important work. In this paper, aiming at a common model of the nonlinear dynamic system, a method for analyzing the nonlinear behavior and the instability of the system is proposed. An example shows that this method is very effective. Related Articles | Metrics

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《Study on Isolation Characteristics of an Electrorheological Fluids SemiActive Engine Mount》 TANG Xin-long;DONG Gui-jun 2010, 30(4): 25-28.  DOI: 10.3969/j.issn.1006-1355.2010.04.007 Abstract ( )   PDF (1096KB) ( )   Based on the original hydraulic overhang the design of the electrorheological fluiols overhang structure with a circular damping channel is carried out. Engine electrorheological fluid model with adjustable damping is established. Equation of state dynamic stiffness and damping angle are derived. The mount dynamic characteristics is simulated using MATLAB code. The simulation results are analyzed, and the effects of the main parameters on the characteristics of overhang are obtained. Related Articles | Metrics

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《Study of a Combinated AirGun Hypocenter for Ocean Exploration》 TAN Yong-jun 2010, 30(4): 29-32.  DOI: 10.3969/j.issn.1006-1355.2010.04.008 Abstract ( )   PDF (1320KB) ( )   The airgun hypocenters, as a type of nonpollution equipment, emit shocking waves for ocean exploration. One of key for designing an airgun hypocenter is how to optimize the characters of shock wave. A novel airgun hypocenter is studied, in which the basic parameters of airgun hypocenter and two different combinations are discussed. Based on analyzing the mechanism of underwater subsidiary wave of airgun hypocenter, six dominant design parameters are found out, they greatly determine the feature of subsidiary wave. The characters of single airgun at different air pressure and submergence depths are investigated by simulation, from which some theoretical supporting for optimal combination of airgun hypocenter can be obtained. Related Articles | Metrics

运载工具振动与噪声

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ptimal Design of Bus Engine，s Mounting System LI Bo-yue 2010, 30(4): 33-35.  DOI: 10.3969/j.issn.1006-1355.2010.04.009O Abstract ( )   PDF (958KB) ( )   Aiming at the bus engine mounting design, the method of “optimization of two dimensional rigidity element” has been proposed. And a computer program of optimal design for bus engines suspension system has been developed with the Matlab software. This program can complete optimal design for the engine suspension rapidly so as to improve the vibration isolation performance of the suspension system effectively. This program is also verified by ADAMS code. This method has been proved to be practical and useful. Related Articles | Metrics

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《Computation Model and Modal Verification for an Engine Mount System Based on Dynamic Stiffness Test》 SONG Xiang-rong;JIN Yong-jun;LI Jian-kang;ZHENG Li-hui 2010, 30(4): 36-39.  DOI: 10.3969/j.issn.1006-1355.2010.04.010 Abstract ( )   PDF (1428KB) ( )   The practicality and reliability of computation model are the key problems in model building. The dynamic model of the linear system does not adapt to the nonlinearparameter system. In this paper, the stiffness and damping parameters of an engine mount system are obtained in experiments. The corresponding mass matrix and stiffness matrix are used for establishing the dynamic computation model of the engine mount system. The model is validated by relative analysis of operational modal and calculated modal. Results indicate that the computation model including dynamic stiffness parameters is more practical than the traditional model of static stiffness. Related Articles | Metrics

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《Research on Damping Material Used in Sea Pipeline Systems》 WANG Yu-ping;ZHANG Dan-cai;YU Yong-feng 2010, 30(4): 40-43.  DOI: 10.3969/j.issn.1006-1355.2010.04.011 Abstract ( )   PDF (1263KB) ( )   Radiation noise from machinery equipment through the pipe system is one of the most important noise sources of submarines. As the extensive applications of floating rafts, the radiation noise from machinery equipment through foundation has already been well controlled. But radiation noise through pipe systems is becoming serious gradually now. The damping tape attached to the pipes surface can absorb vibration energy effectively. It is one of the effective means for reducing vibration and noise of the pipe systems. In this paper, the theoretical analysis and experimental study of the transmission loss of the damping tape are carried out. It is found that this method can effectively reduce the vibration and noise transmitted from the pipeline systems. Result of this research has significance for increasing the concealment of nuclear submarines. Related Articles | Metrics

环境振动与环境噪声

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《Study on Optimal Spotting for Urban Traffic Noise Monitoring 》 WANG Tian-li;XIE Jia-yin 2010, 30(4): 44-46.  DOI: 10.3969/j.issn.1006-1355.2010.04.012 Abstract ( )   PDF (1021KB) ( )   The optimal spotting for urban traffic noise monitoring is discussed in this paper. Taking Harbin as an example, firstly, the monitoring spots are classified applying fuzzyclustering method; and then, the classified monitoring spots are analyzed by using the principal component analysis method to optimize the spotting. The result is good and this method is proved to be feasible. Related Articles | Metrics

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《Influence of Air Conditioner，s Compressor on Vehicles Interior Noise 》 ZHU Ai-wu 2010, 30(4): 47-49.  DOI: 10.3969/j.issn.1006-1355.2010.04.013 Abstract ( )   PDF (1158KB) ( )   In this paper, two kinds of vehicle interior noise caused by air conditioners compressor are studied. It is discovered that (1) the booming noise appears when the rotation speed of the engine reaches about 4750rpm, due to the resonance caused by the powertrain modal frequency of the compressors support and the engines second order vibration frequency; and (2) the beat noise of idling is due to the beat phenomenon caused by the irrational speed ratio of the engine and the air conditioners compressor. Related Articles | Metrics

建筑振动与建筑声学

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《Research on Buildings Vibration Induced by HighSpeed Trains》 LU Hua-xi;LIANG Ping-ying;XU Yan-ping 2010, 30(4): 50-53.  DOI: 10.3969/j.issn.1006-1355.2010.04.014 Abstract ( )   Building vibration induced by highspeed train is an international hot issue. In this paper, four main approaches developed for analyzing building vibration induced by highspeed train, i.e. empirical approach, analytical approach, numerical approach and experimental approach, are introduced. The research status and advance are analyzed, and some problems for further study are presented. Related Articles | Metrics

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《Analysis and Experimental Study on Sound Absorption and Noise Reduction Performance of Some Composite Materials》 CAI He-shan;LI Xiao-xia;ZHANG Wei-bin 2010, 30(4): 54-57.  DOI: 10.3969/j.issn.1006-1355.2010.04.015 Abstract ( )   Two kinds of composite sound absorption materials were prepared using plywood, sponge and foam as main materials. The sound absorption coefficients of these samples were tested through stationary wave tube method and their sound absorption and noise reduction properties were also compared. The results show that the sound absorption performance of the composite materials is remarkably better than those of single materials. In the sound absorption frequency spectrum, the absorption peak of the composite materials is located at 1 000 Hz. The sound absorption performance of the 46mm thick sample of plywoodfoam composite is the best. Its sound absorption coefficient can reach 95.5%. The noise reduction coefficients (NRC) of the composite materials are also obviously superior to those of single materials. The NRC of the three layers sample (36mm thick) of plywood sponge composite and the NRC of the four layers sample (46mm thick) of plywoodfoam composite can reach 0.39 and 0.36 respectively. It is shown that these two composite samples have a good performance in sound absorption and noise reduction. They can meet the needs of modern habitation circumstances. Related Articles | Metrics

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《Research and Development of a New Type Cellular Concrete Based Sound Absorption Material》 ZHOU Dong-liang;PAN Zhi-hua 2010, 30(4): 58-60.  DOI: 10.3969/j.issn.1006-1355.2010.04.016 Abstract ( )   Cellular concrete is one of the quality environmentprotective soundabsorption materials. A new type of cementbased sound absorption material was developed using cellular concrete forming technology. And some additives were added in the cellular concrete. While in the traditional method, only a little of connected pores are generated by binding the aggregates with cement paste. This sound absorption material has good performance and low cost, is easy to prepare, and has no pollution to the environment. Experimental results show that the dosage of air entraining agent, mass density, and the thickness of the component of the material have significant influence on its sound absorption performance. Related Articles | Metrics

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《Study on Influence of Improved Asphalt on the Property of Porous Bituminous Mixture》 XU Qiu-xin;LIU Yan;WANG Yong;ZHANG Ji-liang;YANG Bing 2010, 30(4): 61-63.  DOI: 10.3969/j.issn.1006-1355.2010.04.017 Abstract ( )   With automobile industrys development and urban traffic growth, traffic noise in urban areas increases rapidly, which brings the serious influence on the daily life and work for the residents. Therefore, noise reduction research of bituminous pavements of urban roads is urgent. In order to guarantee the noise reduction effect of the bituminous pavements, the porosity 15%~20% is required for the pavement. Therefore, the material gradation composition, bituminous binder's performance, the asphaltaggregate proportion, and the physical properties of the pavement must be controlled precisely. This article uses experimental method to carry on the design of mix proportion of the porous bituminous pavement material for different aggregate gradation to provide the basis for determination of the noise reduction performance for the porous bituminous pavement materials. Related Articles | Metrics

信号处理与故障诊断

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《Fault Diagnosis of Gears Based on Wavelet Analysis and Fuzzy Neural Network》 YANG Chao;WANG Zhi-wei 2010, 30(4): 64-67.  DOI: 10.3969/j.issn.1006-1355.2010.04.018 Abstract ( )   A gear simulation testbed collecting fault signals was established. A good fault diagnosis result was obtained in simulation experiments by combining feature extraction method based on wavelet analysis with fuzzy neural network. The result shows that the fuzzy neural network is faster and more accurate than the traditional BP neural network in gears fault diagnosis. Related Articles | Metrics

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《Signal Denoising in Wavelet Domain and Its Application in Digital Preservation of Historical Audio Materials》 LI Zhan-hui;LIU Xiao-qiang;LI Bai-yan 2010, 30(4): 68-71.  DOI: 10.3969/j.issn.1006-1355.2010.04.019 Abstract ( )   Audio denoising is the preliminary step in the digital processing of historical audio materials. Wavelet domain denoising is an optional method. But traditional threshold shrinkage method has the tendency to oversuppress the wavelet coefficients in eliminating the HISS noise. This tendency may blur audio frequency and ruin the timbre. In this paper, an adaptive datadriven multithreshold audio denoising method based on wavelet packet transform is proposed. In this method, the optimal threshold value at each terminal node of the wavelet packet tree with best decomposition is derived in a Bayesian framework, and the mean threshold function is presented. The experiments and applications show that in comparison with the formula of hard threshold, this method can retain more original music signals after HISS noise reduction, which adapts the digital music to the auditory response of listeners preferably. Thus, this method can meet the requirements of digital reservation of the historical audio materials in both subjective and objective aspects. Related Articles | Metrics

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《Time Series Distance Approach for RubImpact Fault Analysis of Rotor System Based on EMD-AR Method》 WANG Zhen;QI Gui-bing;JIANG Qin-yu; 2010, 30(4): 72-75.  DOI: 10.3969/j.issn.1006-1355.2010.04.020 Abstract ( )   In this paper, the nonlinear vibration signals of a rotor system with single point local rubimpact faults are decomposed into a number of intrinsic mode functions (IMF) with EMD method. The AR model for each IMF component is then established. Combining the Mahalanobis distance criterion function with KL information, an approach of time series distance analysis for the faults diagnoses is proposed. Experimental results show that this approach is good. Related Articles | Metrics

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《Application of Empirical Mode Decomposition Method in spacecraft Fault Diagnosis》 CHEN Ting-yan;JING Jian-ping;CHEN Tie-feng;JIN Chang-ming 2010, 30(4): 76-80.  DOI: 10.3969/j.issn.1006-1355.2010.04.021 Abstract ( )   Independent fault diagnosis for orbited spacecraft in real time is always the bottleneck in the development of aerospace engineering. In this paper, the empirical mode decomposition (EMD) is employed for fault diagnosis of moving component parts of spacecrafts. The stepout fault characteristic is extracted effectively and the base frequency is obtained. This method provides with the basis for fault diagnosis of orbited spacecrafts under the blackbox condition. In addition, in comparison with FFT and wavelet analysis, it is found that the EMD method is more efficient and advanced in the fault diagnosis of moving component parts of spacecrafts. Related Articles | Metrics

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《Fault Diagnosis of Abnormal Vibration in Aero Engine Bench Test》 QIN Hai-qin;XU Ke-jun;LIU Zhong-hua;WANG Yong-qi 2010, 30(4): 81-84.  DOI: 10.3969/j.issn.1006-1355.2010.04.022 Abstract ( )   Based on the analysis of vibration signal measured in an aeroengines case testing and the analysis of the structural characteristics of the aeroengine, the abnormal vibration in bench test is studied. The result shows that the clearance and eccentricity of the bearing system of the lowpressure turbine are the main contribution to the abnormal vibration. It also shows that combining modern signal process technique with pertinent analysis method, the fault in aeroengine can be located quickly and accurately. Related Articles | Metrics

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《Study on Abnormal Sound Monitoring for Cylinders Head of Motorcycle Engine》 YANG Cheng;WANG Zhong-fang;YANG Zhen-dong;ZHANG Bin 2010, 30(4): 85-88.  DOI: 10.3969/j.issn.1006-1355.2010.04.023 Abstract ( )   Aiming at the vibration signals of abnormal sound from cylinder's head of motorcycle engine, characteristic values of the abnormal sound of each cycle are computed in timedomain using statistical functions. Comparing these characteristic values with the frequency spectrum of the normal engine, the characteristic frequency of the abnormal sound is found. Through the order analysis, the energy distributions of both normal and abnormal vibration signals of engines are studied. And the energy differences of the vibration signals of various orders are analyzed. The results show that these methods can identify abnormal sound of the cylinders head effectively. Related Articles | Metrics

减振降噪设备和器材

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《Experimental Study and Performance Analysis of Air Spring Vibration Isolation System》 MAN Nan;ZHANG Xinna;LI Dongsheng 2010, 30(4): 89-92.  DOI: 10.3969/j.issn.1006-1355.2010.04.024 Abstract ( )   Vibrationtesting and analysis of vibration isolation performance of an air spring vibration isolation system were carried out. The accelerometer was installed on the vibration isolation testing foundation, and the vibration accelerates, amplitudes and passingfrequency band of the vibration isolation system were measured using hammering method. The results were compared with the parameters obtained in ground vibration testing. In addition, the optimal position of the testing foundation and the optimal internal pressure of the air spring were found for obtaining the highest effect of the isolation system. The results show that the air spring vibration isolation system can isolate vibration from the ground effectively. Related Articles | Metrics

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《Research on Vibration Resistance of Crystal Oscillator》 ZHANG Jing;LIU Ping;CHEN Min;YAN Xiao-long 2010, 30(4): 93-96.  DOI: 10.3969/j.issn.1006-1355.2010.04.025 Abstract ( )   The phenomenon of irregular wave output of crystal oscillator in the random vibration test is studied in this paper. Using the resonance free technique and the knowledge of flat spring, the dimensions of the flat spring are determined; the flat spring is installed and tested; and the problems in the testing is resolved. Related Articles | Metrics

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《Summary of Kinds and Features of Damping Alloys》 SONG Guo-yang;MU Long 2010, 30(4): 97-99.  DOI: 10.3969/j.issn.1006-1355.2010.04.026 Abstract ( )   Damping alloy is a kind of new functional materials. Using them to fabricate the component parts of vibration source, many vibration and noise problems in mechanical manufacture and some other fields can be solved effectively. In this paper, the kinds, features and applications of damping alloys are summarized. Their damping and mechanical properties are compared one another. The results provide a new idea and a reference for material choice for damping and noise reduction. Related Articles | Metrics

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《Finite Element Method for Prediction of Acoustic Attenuation Characteristics of StraightThrough Perforated Tube Silencer with Steady Air Flow》 XU Bei-bei;JI Zhen-lin;KANG Zhong-xu;XU Hang-shou 2010, 30(4): 100-103.  DOI: 10.3969/j.issn.1006-1355.2010.04.027 Abstract ( )   The finite element method (FEM) is applied to predict acoustic attenuation characteristics of straightthrough perforated tube silencer with steady air flow. The finite element formulation is carried out, and the numerical method and procedure for predicting the acoustic attenuation characteristics are introduced. Since the convective effect is taken into consideration, the present method is suitable for the case with steady air flow. Transmission loss of straightthrough perforated tube silencer is then predicted using threedimensional finite element method. The numerical results show that the acoustic attenuation effect is raised in the medium and higher frequency range as the Mach number of the flow is increased. It is suggested that in order to predict the acoustic attenuation characteristics of straightthrough perforated tube silencer accurately, the influence of steady flow on the sound propagation in the silencer should be considered. Related Articles | Metrics

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《Experimental Study on Acoustic Characteristics of the Muffler with Inserted Pipes》 DU Jiang;OUYANG Hua;DU Zhao-hui 2010, 30(4): 104-109.  DOI: 10.3969/j.issn.1006-1355.2010.04.028 Abstract ( )   The experimental study was carried out on both the internal and external acoustic characteristics of the muffler with inserted pipes. The lengthtodiameter ratio L/D of the pipes is 3.98 and the air velocity in the pipes is from 10m/s to 100m/s. The effects of air velocity and structure parameters on the acoustic characteristics of the muffler were studied. The acoustic characteristic mechanism of the muffler with inserted pipes was analyzed according to the air vortex mode in the cavity of the muffler and the acoustic modes of both cavity in muffler and tail pipe. It is found that both the internal and external acoustic characteristics of the muffler are influenced greatly by the air velocity. The acoustic characteristics of insertedpipe muffler are closely related to the acoustic mode of cavity in muffler and the acoustic mode of tail pipe, but they are essentially independent of the vortex mode of the air regeneration noise in the muffler. Related Articles | Metrics

标准规范与评价

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《Research on Noise Standards and Measurement for Motor Vehicles》 YANG An-jie 2010, 30(4): 110-114.  DOI: 10.3969/j.issn.1006-1355.2010.04.029 Abstract ( )   The development and current status of China's automobile noise standards are introduced and compared with foreign regulations. The problems in acceleration noise testing outside vehicles are analyzed. The difference of noise standard levels for the medium and heavy trucks and large buses between the developed countries and our country is pointed out. It is also indicated that China has not yet worked out the standard for interior noise and uniformspeed noise limits for motor vehicles. Although there are stationary noise limits and corresponding measurement methods in our country, they are rarely executed in actual annual inspection. Finally, in order that China becomes a powerful country for automobile manufacture and export, the work we need to do in the aspect of noise control is suggested. Related Articles | Metrics

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《Subjective Evaluation Research of BClass Cars Interior Sound Quality》 GAO Yin-han;SUN Qiang;LIANG Jie;XIE Jun 2010, 30(4): 115-118.  DOI: 10.3969/j.issn.1006-1355.2010.04.030 Abstract ( )   The interior noise samples from six types of Bclass cars driven at different speeds were selected as the evaluation objects. The subjective evaluation test of sound quality preference was carried out with the paired comparison. Several objective psychoacoustical parameters of these samples were calculated. By means of linear correlation and multidimensional regression analysis, a mathematical model for subjective evaluation of noise preference was established. The results indicate that the Bclass cars sound quality preference under the constantvelocity driving condition is affected by two parameters: loudness and sharpness. Related Articles | Metrics

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《Sound Quality Preference Evaluation and Objective Analysis for Vehicle，s Door Closing Sound》 WU Jing;CHEN Jian 2010, 30(4): 119-122.  DOI: 10.3969/j.issn.1006-1355.2010.04.031 Abstract ( )   The left front door closing sound samples at driver's left and right ears of 13 kinds of cars were collected as evaluation objects. Paired comparison method is applied for the subjective preference evaluation. Then, the characteristics of the sound samples which get high preference degree in the subjective evaluation test are studied and summarized. The main psychoacoustic parameters are calculated and the relationship between psychoacoustic parameters and subjective preference is analyzed. Related Articles | Metrics

振动噪声测试技术

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《Study on the Technique for Measuring Noise in Pipe Lines 》 LIANG Xiang-dong 2010, 30(4): 123-124.  DOI: 10.3969/j.issn.1006-1355.2010.04.032 Abstract ( )   A method for measurement of the fluid noise in pipe lines is proposed. The equipment for this method includes an additive small water tank. With this method, the water noise signal can be separated from the pressurenoise mixed signal in the pipe lines. The testing results show that the characteristics of the water noise in the pipe lines can be measured effectively with this method and this equipment. Related Articles | Metrics

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《Vibration Measurement and Analysis of Main Reducer Hypoid Gear of Vehicles Rear Axle》 HAN Shao-jun;ZHANGBing-wei;LI Zheng-tian;WAN Shang-gao 2010, 30(4): 125-128.  DOI: 10.3969/j.issn.1006-1355.2010.04.033 Abstract ( )   The main reducer hypoid gear of vehicle's rear axle and the frequency spectrum method are briefly introduced. Then the design of the testing system of the main reducer hypoid gear and its testing method are elaborated. The results of the testing are analyzed with the method of frequency spectrum, and the main reasons of the vibration of the main reducer hypoid gear are researched. A scientific basis is provided for reducing the vibration and noise of main reducer hypoid gear. Related Articles | Metrics

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《Prediction of Radiation Noise of Gearbox Using FEABEA Method》 ZHOU Li-ting;LI Hong-kun;GUO Yi-jie 2010, 30(4): 129-132.  DOI: 10.3969/j.issn.1006-1355.2010.04.034 Abstract ( )   In this paper, the gear transmission system is simulated by dynamic simulation software. The dynamic response of the gearbox is calculated by means of the finite element method. The structure noise of the gearbox is predicted by using boundary element method with the obtained dynamic response as the boundary condition. Meanwhile, the sound intensity of the structure noise of the gearbox is tested and compared with the predicted result. The results indicate that this method can accurately predict the radiation noise characteristics of the gearbox. This work provides a reliable basis for gearbox noise control and structural optimization. Related Articles | Metrics

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《Study on Noise Prediction Model of Weining Railway Section in NeijiangKunming Line》 DAI Ben-lin;;HUA Zulin;;HE Yu-long;LI Wei;GU Li 2010, 30(4): 133-137.  DOI: 10.3969/j.issn.1006-1355.2010.04.035 Abstract ( )   Due to the requirement of railway noise evaluation, the Germany Schall03 noise forecasting model is amended according to the actual railroad situation in the western mountain areas of our country. The amended Germany Schall03 forecasting model is then used to forecast the railway noise in Weining section of NeijiangKunming line. Comparing the predictive value with the measured data, it shows that using the amended model to predict the noise of this railway section is feasible and effective. The work in this paper complements the deficiency of the research of railway noise prediction in the western mountain area of our country. Related Articles | Metrics

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《Detection Mechanism Analysis of CoinTapping Response Signals of Carbon Electrodes》 CAO Xiaolin;WANG Shuangwei;WEI Zhigang;SHEN Xiaobo;GAO Zhihua;HOU Yingzhe 2010, 30(4): 138-143.  DOI: 10.3969/j.issn.1006-1355.2010.04.036 Abstract ( )   Wavelet and rough sets are used to analyze the detection mechanism of cointapping response signals from carbon electrodes. After 8 layers decomposition of the response signals using db9 wavelet basic function, 9 wavelet channels are obtained. Then, rough sets are used to delete the redundant character channels in the 9 wavelet channels. The results show that channels D5, D6, D7 and D8 are the effective character channels to distinguish defective electrodes from quality electrodes. Furthermore, research on detection mechanism shows that the difference of cointapping response signals between defective and quality electrodes is distinguished from the difference of resonance phenomena in base frequency and low order harmonic wave. In addition, an effective method for binary attribute importance analysis, which can delete redundant attributes with null importance in pairs, is proposed. And the core of knowledge expression system can be found with this method. Related Articles | Metrics

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《Neural Network Predictive Control of Cantilever Beam with Piezoelectric Sensors and Actuators》 WANG Ercheng;ZHANG Jingjun;MA Xiaoyu;LIU Jie 2010, 30(4): 144-149.  DOI: 10.3969/j.issn.1006-1355.2010.04.037 Abstract ( )   Piezoelectric sensors or actuators are bonded to the surfaces of a flexible cantilever beam. The finite element method is used to build the model of the beam. The dynamic response data of the piezoelectric smart structures is obtained through the FEM analysis. According to the nonlinear approximation capability of neural networks, a dynamic recursive BP neural network is used to identify the piezoelectric vibration system, and the predictive model is built. On the basis of the neural network predictive model, the generalized predictive control algorithm is proposed to control the piezoelectric vibration system and to suppress the undesired vibration of the structures. Simulation results demonstrate the excellent performance of the developed control system. It has some significance for guiding the application of intelligent control algorithms in smart structures. Related Articles | Metrics

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《Study on Noise Suppressing Performance of Constrained Layer Damping Structure》 YANG Qing;WANG Xin;ZHANG Wenwei;Zhu Jie 2010, 30(4): 150-152.  DOI: 10.3969/j.issn.1006-1355.2010.04.038 Abstract ( )   Constrained layer damping, as one type of the surface damping methods, is usually applied to solve the vibration and noise problems of metal plate structures. The loss factor and storage modulus of the damping material are usually used to evaluate the damping performance of the material. But this method can not be employed to evaluate the vibration and noise control performance of the constrained layer damping effectively and directly. In this paper, a new method is introduced to solve this problem. In this method, sinusoidal scanning is adopted and the vibration of a simply supported beam is excited by the quasiwhite noise random vibration. Through the analysis of the response, the vibration and noise control effect of the constrained layer damping is expressed. Related Articles | Metrics

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《Benefit Analysis of VibrationReduction of Automatic Balancer》 LIU Wenqian;;TAN Qing;XIE Yanqin;NIE Weidong 2010, 30(4): 153-157.  DOI: 10.3969/j.issn.1006-1355.2010.04.039 Abstract ( )   The background of automatic balancer study is introduced. The working principles, the characteristics of balancing, and the benefit of vibration reduction of three types of automatic balancers, the rollingball type balancer, the hammer type balancer and the liquid type balancer, are studied. It is suggested that the multiple of the vibration reduction be adopted as a quantitative index for the benefit evaluation. Comparative analysis shows that the rollingball type balancer has the best benefit of vibration reduction among the three types of balancers. In an ideal situation，the rotor can be brought to a complete balance state and the multiple of vibration reduction can reach infinity. While for hammer type balancer, the multiple of vibration reduction is much larger than unity in the ideal situation. Comparatively, the vibration reduction benefit is poor for liquid type balancer. Its multiple of vibration reduction is between 1 and 2. Related Articles | Metrics

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《Study on New Type Noise Elimination Structure at Ventilation Vent of Indoor Transformer Substation》 JIN Wei;CAI Jun 2010, 30(4): 158-160.  DOI: 10.3969/j.issn.1006-1355.2010.04.040 Abstract ( )   The problems of heat emission and noise control at the ventilation vent of an indoor transformer substation were studied. The toandfro reflection noise elimination structure was designed and used in the noise control of Xuanhua transformer substation. It is shown that the toandfro reflection noise elimination technique is available in noise control with heat emission and ventilation. Related Articles | Metrics

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《Dynamic Design of Fixture for Electronic Component Testing》 ZHAI Yinjiang;CHEN Jian;LUO Yujun;WEN Zhiming; 2010, 30(4): 161-164.  DOI: 10.3969/j.issn.1006-1355.2010.04.041 Abstract ( )   In order to test the reliability of electronic components of automobiles, the vibration reliability testing is necessary. The fixture, which is used to clamp and fix the electronic components, is one of the most important components in the testing. The dynamic performance of the fixture has great influence on the vibration test. According to the appearance and the location of the electronic components, a threedimensional model of the fixture was constituted. The modal frequency and vibration modal were calculated using FEM. Due to the result of analysis, the structure of the fixture was amended. And its dynamic performance can meet the testing request after the amendment. Related Articles | Metrics

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《Modal Analysis of Refrigerators BackPlates by Testing》 GU Mingliang;ZHAO Xiangyang 2010, 30(4): 164-165.  DOI: 10.3969/j.issn.1006-1355.2010.04.042 Abstract ( )   There are 3 ways to reduce refrigerators noise: reducing the sound source, optimizing the sound delivery path, and repressing the response. In this paper, the second way is discussed only. Through the modal analysis of the backplates of some Haier refrigerators, their natural frequencies and vibration modes are found. The optimal design of the backplate structure is presented. The resonance between the backplate and the entire refrigerator can be avoided and the noise can be reduced. Related Articles | Metrics

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《Experimental Research on Acoustic Emission of Bolt Joints in Vibration Environment》 LONG Lin;WANG Ning;TAO Junlin;YAO Yong 2010, 30(4): 166-170.  DOI: 10.3969/j.issn.1006-1355.2010.04.043 Abstract ( )   Bolt joints are widespread used. But loose bolts may result in disastrous consequences. With acoustic emission (AE) technology, a collection of acoustic emission signals in preliminary tests is carried out on a vibration platform to detect the state of bolt joints. Analyzing a large amount of AE signals collected in the tests, signal characteristics corresponding to the bolt joints state under different twisting moments are found. And the loose state of the bolts is identified. Related Articles | Metrics

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《Noise Control for Cooling Towers in a Market of Shanghai》 GU Xuheng;LIN Zecong;YAO Jianguan;Marc Buret 2010, 30(4): 171-174.  DOI: 10.3969/j.issn.1006-1355.2010.04.044 Abstract ( )   There are five groups of cooling towers on the roofs of a market in Shanghai. They cause noise pollution to the adjacent residents. Thus, noise control is necessary. Through the measurement and analysis of noise, Supreme Environmental Research (Shenzhen) Ltd provides an optimized design for the noise control with low cost, easy maintenance and minimum influence on the current equipment. The idea in this design presents a reference for similar engineering projects. Related Articles | Metrics

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《Research on Noise Control Technique for WaterSource Heat Pumps》 DI Wei;CHEN Changzheng 2010, 30(4): 175-177.  DOI: 10.3969/j.issn.1006-1355.2010.04.045 Abstract ( )   Watersource heat pumps have been widely used. However, their noise seriously influences the residents. Based on the measurement data and the analysis of field experiments, the measures of vibration isolation and sound absorption to control watersource heat pump noise are presented, and excellent result is obtained. Related Articles | Metrics

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《Research on the Technique of Noise and Vibration Control of a Water Injection Station in Daqing Oilfield 》 ZHANG Gang 2010, 30(4): 178-181.  DOI: 10.3969/j.issn.1006-1355.2010.04.046 Abstract ( )   The technique of sound absorption, sound insulation and vibration isolation is used for noise reduction of the La13 water injection pump house of the sixth oil extraction factory of Daqing oilfield. The Raynoise software is employed to simulate the sound fields of the pump house before and after the noise control treatment. The most economical noise control scheme is determined by the simulation. The technique of noise reduction and the experience of its application are introduced systematically. Related Articles | Metrics