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18 June 2011, Volume 31 Issue 3 Previous Issue    Next Issue
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2.振动理论与数值解法
3.运载工具振动与噪声
4.环境振动与环境声学
3.运载工具振动与噪声
4.环境振动与环境声学
6.信号处理与故障诊断
7.减振降噪设备和器材
8.标准规范与评价
9.振动噪声测试技术


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2.振动理论与数值解法

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Parameter Calculation and Analysis of Vibration Isolation System in Towed Array Sonar JIANG Guo-he;XUE Feng;TANG Zeng-yan 2011, 31(3): 1-4.  DOI: 10.3969/j.issn.1006-1355-2011.03.001 Abstract ( )   In order to investigate the influence of vibration isolation system parameters of towed array sonar on its vibration isolation effect，a three-dimensional fluid-structure coupling field model is constructed by means of ANSYS. The influence of vibration isolation is calculated by using material parameters of the vibration isolation system. Numerical simulation results are compared with experimental results. Results of the parameter calculation provide a base for the study of vibration capabilities of the isolation system. The results and conclusions have reference values for improving the capability of the vibration isolation system. Related Articles | Metrics

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Experimental and Numerical Analysis of Inverted Pendulum with a Location Limit ZHANG Jian-bo;FENG Qi 2011, 31(3): 5-10.  DOI: 10.3969/j.issn.1006-1355-2011.03.002 Abstract ( )   An experimental system for an inverted pendulum with a location-limit was designed and developed. The mechanical model of the system was established. Through experiments and numerical analysis, the responses of the system in the cases of periodic and random excitations are discussed. Some complicated nonlinear dynamic behavior of the system is revealed. It is found that the noise has some impact on the system behavior. The conclusions will be useful for design and analysis of the structures with gaps. Related Articles | Metrics

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Control of Nonlinear Behaviors of an Active Magnetic Bearing-Rotor System SUN Bao-Cang;Rongsheng Liang;Wei CHEN 2011, 31(3): 11-14.  DOI: 10.3969/j.issn.1006-1355-2011.03.003 Abstract ( )   In this paper, the nonlinear dynamical behaviors of an active magnetic bearing-rotor system are investigated. In order to control the vibration of the system, a state feedback method is adopted. It is theoretically proved that the controlled system can be approximately divided into two asymptotically stable subsystems near the origin. Based on this conclusion, kinematic responses to both controlled and uncontrolled systems are analyzed by numerical simulations to verify the validity of the control scheme. Mutual comparison of the results of both systems reveals that the state feedback control scheme presented here can effectively control not only periodic vibrations, but also quasi-periodic and chaotic vibrations. Related Articles | Metrics

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Experimental Research on the Vibration Characteristics of Moving Coil - rubber Structure XU Wei;ZENG Xin-wu;SUN Hai-yang;GONG Chang-chao 2011, 31(3): 15-18.  DOI: 10.3969/j.issn.1006-1355-2011.03.004 Abstract ( )   A measurement system for vibration displacement of the moving coil-rubber structure was set up using eddy current sensors technique. The vibration characteristics of system using rubber with Shore A hardness of 40 and 50 (40oand 50o) were studied respectively. The results show that the moving coil-rubber system can be considered as a single-degree-of- freedom system. For small distortion, the main resonance frequency rising gradient decreases with the pre-compression increasing. The effective band width of the system with 50o rubber is wider than that with 40o rubber. It is also found that the rubber’s equivalent stiffness decreases with the increasing of the exciting signal. Under the condition of small initial distortion, distortion of the displacement wave can be reduced by increasing the rubber’s pre-compression. Related Articles | Metrics

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Research of Improved Algorithm for Blind Source Separation Based on Second-order Statistics LV Shu-ping;FANG Xing-jie 2011, 31(3): 19-23.  DOI: 10.3969/j.issn.1006-1355-2011.03.005 Abstract ( )   It is known that using non-stationary and structural characteristics of signal timing of the second-order statistics (different time-delay correlation matrix) can roughly estimate the instantaneous linear-mixture blind-source signal. With the increasing of time delay [τ], only using single delay covariant equalization will ignore the time-varying characteristics of the signal, so that the performance of algorithm may not be ensured. Through the analysis of average characteristics of matrix, the improved algorithm for blind source separation based on the second-order statistics is presented in this paper. Segmenting a set of equalized delay-related functions, calculating the mean values of the two time-delay matrixes, and using a quasi joint approximate diagonalization, the optimal U-matrix can be estimated. Then, the robust source estimates can be obtained after all. Both performance index analysis and simulations show that the new algorithm can make up for the deficiencies of the original algorithm, and successfully separate the signal. Related Articles | Metrics

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Study on Mathematical Models of Optimization Design for Vibration Rreduction of Hybrid Steel-composite Structure YANG De-qing;CHEN Jing;GUO Wan-tao;LUO Fang 2011, 31(3): 24-28.  DOI: 10.3969/j.issn.1006-1355-2011.03.006 Abstract ( )   Composite materials are widely used in engineering structures for its excellent performances of high damping loss factor, low density, high special strength, high special stiffness etc. Design of composite structure is a combination process of the mechanical performance with the materials design. For quite a few design parameters and complex influencing factors in the process, the optimal design becomes very important. Based on the different vibration reduction evaluation criterions, various structural dynamic optimization design models can be formulated. And their effects for vibration reduction can be quite different. In this paper, a synthetic evaluation method, considering vibration level difference and power flow level difference with structure’s weight or power flow at the evaluation points as objective functions, is presented. Taking the structural dynamic optimization design of the steel-composite mounting as an example, the corresponding mathematical model is established. By introducing multi-island genetic method, the optimization problems are solved. Computational results show that using this model for composite structure optimization, more feasible solution than that using conventional optimization model can be obtained. Related Articles | Metrics

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Optimization of Vibration Isolation System for Double - fed Generator in Windmill LIU Jian-xun;HU Wei-hui;LIN Sheng;ZHANG Ya-xin 2011, 31(3): 29-32.  DOI: 10.3969/j.issn.1006-1355-2011.03.007 Abstract ( )   Generator is one of the most important devices in Windmill. Its normal and smooth operation without resonance must be guaranteed. However, it was found that abnormal vibration appears during the operation of a domestic double-fed generator. Theoretical computation and vibration test showed that the performance of generator’s mount didn’t match the generator. Thus, the generator’s mount with different stiffness were installed and the vibration test was carried out. Finally, a suitable mount was found. This work provides some reference for selection of generator’s mounts. Related Articles | Metrics

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Research of AANC Secondary Path Modeling Method YANG Hao;WU Ya-feng;WANG Chun-yun;CHU Ni-Sheng 2011, 31(3): 33-36.  DOI: 10.3969/j.issn.1006-1355-2011.03.008 Abstract ( )   Secondary path modeling is a key issue of adaptive active noise control (AANC) system. An impulse response measurement based on time stretch pulse (TSP) signal is used in this paper. TSP signal has the characteristics of distributing the pulse energy in a period of time. The impulse response function of the tested system with TSP signal can be reconstructed by gathering the scattered energy in the response signal. The method is applied to secondary path modeling, and 20dB and 14dB noise reduction is respectively obtained in simulations and experiments. The results show that the secondary path modeling method based on TSP is simple, accurate and very suitable for practical ANC engineering test. Related Articles | Metrics

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Dynamic Analysis of Rotor System Coupled by Rubber Bearings LI Fang; SHUAI Chang-geng;HE Lin;YANG Xue;LI MING 2011, 31(3): 37-41.  DOI: 10.3969/j.issn.1006-1355-2011.03.009 Abstract ( )   Mathematical model of a large rotor system supported on rubber bearings is proposed and its dynamics is discussed in this paper. Firstly under the assumption of small perturbation, the dynamic characteristics of rubber bearing is described by Kelvin-voigt model. Then based on the analytical mechanics the motion equations are deduced. For a typical ship propulsion system, a numerical analysis is carried out. The results show that the vibration of the lowest modal is mainly from the propeller, and even at the low rotating speed the amplitude on the propeller rubber bearing under propeller unbalance is larger than the thickness of water film of the rubber bearing in general, consequently phenomena of the stick-slip, spirant and wear between rubber staves and rotor may be produced. Related Articles | Metrics

3.运载工具振动与噪声

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Fuzzy Control in Modal Space for Ride Comfort with MR Damper Bo Wang;Rongxiu Wang 2011, 31(3): 42-46.  DOI: 10.3969/j.issn.1006-1355-2011.03.010 Abstract ( )   Based on the 3-D vehicle model with 7 degrees of freedom, a dynamic model with 7+k degrees of freedom is introduced in this paper for the comfort analysis. In this model, the effects of the passengers and the drivers and their seats are considered. They are represented by k mass-spring subsystems which are incorporated into the 3-D model. With this model, the closed loop dynamic mathematical model is derived to simulate the dynamic behavior of the system. To establish the optimal semi-active control rules, the modal space control method and the linear quadrate optimal theory (LQR) are applied. Numerical examples of a car with 11 degrees of freedom are employed to investigate the validities of this approach. The results obtained from the numerical simulations demonstrate the applicability and suitability of both the 3-D vehicle model with 7+k degrees of freedom and the modal space control method. Related Articles | Metrics

4.环境振动与环境声学

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Performance Analysis of Damping System of Sedan SUN Jian-min 2011, 31(3): 47-50.  DOI: 10.3969/j.issn.1006-1355-2011.03.011 Abstract ( )   Vertical vibration acceleration of sedan’s body is taken as the evaluation index of the damping performance, and the indexes for vehicle handling and stability are studied too. The dynamic performance of the damping system of the sedan is studied for improving its riding comfort and handling stability. Based on the amplitude-frequency characteristics of the body acceleration of the sedan, the dynamic deflection of damping system, and the dynamic load between the wheel and road, the damping performance of the sedan is analyzed. It is indicated that the study on variable damping system is an important measure for improving the vibration performance of sedans. Related Articles | Metrics

3.运载工具振动与噪声

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Analysis and Solutions of Idle Vibration Problem for 6830 CR1 Bus HAN Tian;JIN Ling;YIN Zhong-jun;ZHANG Lei 2011, 31(3): 51-54.  DOI: 10.3969/j.issn.1006-1355-2011.03.012 Abstract ( )   Aiming at the problem of large vibration in the idle state, the vibration testing and hammering modal experiment were done for 6830CR1 bus. The natural frequency and intrinsic characteristics of the entire bus were obtained. It is found that the main factor influencing the bus vibration is the vibration of chassis beam transmitted from the engine, and this factor is closely related with the idle speed. Through the structural simulation analysis of the chassis and comparison of the result with that of the modal testing, it is determined that the bus vibration is a coupling problem between the idle operating frequency and the natural frequency of the chassis. Finally, the phenomenon of coupling resonance is eliminated by improving the local structure of the chassis. Related Articles | Metrics

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Analysis and Extraction of Automobile Chair Electric Slides’ Characteristic Signals SU Dong;WANG Jin-e;XIA Tian-liang 2011, 31(3): 55-59.  DOI: 10.3969/j.issn.1006-1355-2011.03.013 Abstract ( )   During the detection of automobile chairs’ electric slides, the characteristic signals related to the comfort characteristic have been extracted from the vibration signal, and its power spectrum density is chosen as one of the criteria for quality control of products. Based on the demodulation of the second-order circulation statistics of cyclic spectrum density (CSD), the CSD slice chart of the vibration signal of the products is analyzed. And the characteristic modulation signals are obtained. As a result, the defect frequencies which effect the riding comfort are obtained according to their respective power, and the products quality can be well evaluated Related Articles | Metrics

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Modeling of Acoustic Characteristics of a Cab with Response Surface Method and its Application WANG Bin-xing;ZHENG Si-fa;ZHOU lin;LIAN Xiao-min 2011, 31(3): 60-64.  DOI: 10.3969/j.issn.1006-1355-2011.03.014 Abstract ( )   Sound absorbing materials have been widely used in the vehicle noise control. In this paper, the response surface method is applied to the acoustic modeling of the cab of a heavy truck with a variety of sound absorbing materials attached. Design variables are determined with the panel’s acoustic contribution analysis, and the design of the experiments is made. A simulation model of the cab with the consideration of sound absorption characteristics is built to carry out the designed experiments. With the obtained response variables, the response surface model of the sound pressure on the side of the driver’s right ear is built. The effectiveness of the model is validated. The response surface model has been applied to the thicknesses optimization of the sound absorbing materials for different panels of the cab. It shows that after the optimization, the thicknesses of sound absorbing materials are reduced, and the effect of noise reduction is improved at the same time. Related Articles | Metrics

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Study on Tire Pressure Affecting Noise and Vibration of vehicle XIONG Jian-qiang;;HUANG Ju-hua;LIAO Qun 2011, 31(3): 65-68.  DOI: 10.3969/j.issn.1006-1355-2011.03.015 Abstract ( )   The influencing factors of noise and vibration of vehicles are material, tire pressure, vehicle’s structure, road conditions, and so on. This paper analyzes the influence of the inflation pressure of the tire on the noise and vibration of the vehicles. According to the experimental data and theoretical analysis, tire rigidity and natural frequency will increase with the rise of tire’s inflation pressure; suspension and auto vibration will vary evidently with the change of the tire’s pressure; the tire’s pressure has some influence on air pumping noise; the influence of the tire’s pressure on tire’s noise level is low and irregular; the rise of the tire’s pressure will decline the capability of tire’s vibration absorbing and increase the sense of vibration and shock, and will also reduce the riding comfort of the vehicle. The reasonable tire’s pressure is important for reducing the noise and vibration of the entire vehicle. Related Articles | Metrics

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Characteristic Analysis of Vibration and Noise for Heavy Vehicles Gearbox HUANG Ping-ping;MA Wei-jin;GE Yu-min;WANG Jun-yuan 2011, 31(3): 69-72.  DOI: 10.3969/j.issn.1006-1355-2011.03.016 Abstract ( )   Aiming at the operating characteristics of heavy vehicle’s gear box, a vibration and noise testing of the gear box on neutral gear, ten front motions and two reverses was carried out. The measured signals were analyzed in the time domain and the spectral frequency domain. The results have some significance for understanding the characteristic of the vibration and noise of the gearbox and in quality evaluation of the gearbox based on the vibration and noise signals. Related Articles | Metrics

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Feasibility Analysis of Identification of Traffic Flow State with Sound Detection Approach SHI Wei;;LIU Ling-ling;CHEN Wei-hua;ZENG Fu-jun 2011, 31(3): 73-75.  DOI: 10.3969/j.issn.1006-1355-2011.03.017 Abstract ( )   In this paper, the optimal velocity model of traffic flow is employed to obtain the information of vehicles running on the road via numerical simulation. According to the derived formula of noise prediction, the sound pressure level of point noise is computed. Comparing the characteristic of traffic flow with the change of sound pressure level, it is found that the change of the flow rate curve is similar to that of the sound pressure level detected on the road. It means that the method of sound detection is useful to distinguish the state of traffic flow under certain conditions. Related Articles | Metrics

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The body Structure Dynamic Characteristics and Acoustic Modal Analysis of A-type Metro Vehicle 2011, 31(3): 76-79.  Abstract ( )   The finite element model（FEM）of the car body structure and interior acoustic cavity of the A type subway were established for their modal analysis. The structure modal analysis of the car body shows that the designed car body satisfy requests of the dynamic design standard., However, the end wall should be strengthened and the connect intensity between ceiling and side walls should be improved in order to improve the structure dynamical characteristics and their fatigue life. The acoustic modal analysis of the interior cavity shows that the symmetrical characteristics of the car body structure decide the same symmetry of the interior sound field in its three coordinate directions. As the result, the mode shapes are symmetrical also in its three directions. The result suggests that the resonance frequency of the interior sound field and the mode shapes are decided by its geometric shape. Related Articles | Metrics

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Development and Application of the Software for Acoustic Environment Prediction in the Vicinity of Rail Transit Lines GONG Kai;LIU Lin-ya 2011, 31(3): 80-84.  DOI: 10.3969/j.issn.1006-1355-2011.03.019 Abstract ( )   Acoustic environment prediction in the vicinity of rail transit lines has become an international hot topic in railroad engineering. Most of rail transit lines are constructed near or through the urban areas, therefore, the rail transit noise often makes serious impact on the residents in the vicinities of the lines. To effectively control the rail transit noise, Visual BASIC language is adopted to develop the software for rail transit acoustic environment prediction. The results of noise prediction by the software are compared with the measured data of the acoustic environment in the vicinity of a rail transit line, and the reliability of the software is verified. This work is an attempt for routinization, visualization and facilitation of noise prediction by using software. Related Articles | Metrics

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Noise Test and Objective Parameters Analysis of Sound Quality for High Speed Trains YE Gui-xin;LIU Yan;YANG Bing;JIANG Chang-ying;ZHONG Zhi-fang 2011, 31(3): 85-88.  DOI: 10.3969/j.issn.1006-1355-2011.03.020 Abstract ( )   In vibration and noise reduction design of high speed train, sound quality has become an important indicator of comfort evaluation. In this paper, based on the theory by Zwicker who presented objective quantificational methods for subjective evaluation of the noise, the experimental data of internal noise of high speed railway trains is analyzed through the calculation of four objective evaluation parameters of noise: loudness, sharpness, roughness and fluctuation strength. Finally, the status and distribution regulations of various psychoacoustics parameters are obtained in the typical position of the train driven at several constant speeds. This work provides some reference basis for sound quality research of the high speed railway trains. Related Articles | Metrics

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Prediction of Wheel - rail Noise by Operating High Speed Train YANG Xin-wen;ZHAI Wan-ming;HE Zhen-xing 2011, 31(3): 89-94.  DOI: 10.3969/j.issn.1006-1355-2011.03.021 Abstract ( )   With the rising of train operation speed, wheel/rail noises are significantly increased. Based on vehicle-track coupled dynamics, random vibration theory and acoustics theory, a model is produced to predict wheel/rail noises by high speed train operating due to wheel and rail surface roughness, geometric discontinuity in contact, and so on. And the corresponding software WRNOISE（Wheel/Rail Noise）is developed. Compared with existing prediction model TWINS (Track-Wheel Interaction Noise Software), the result shows that the main frequency ranges and trends of the noise of TWINS software simulation values and the present model computation values are consistent. Compared with the model STTIN (Simulation of Train-Track Interaction Noise), the present prediction model can be more fully taken into account the vibration and noise contribution in the axial direction of wheels and the lateral direction of rails. Compared with the noise test values of the high-speed train running on ballasted track and slab track, there are some differences between prediction values of the present model WRNOISE and noise test values, but both trends are in agreement mutually from the viewpoint of wheel-rail noise radiation dominant frequencies. Related Articles | Metrics

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Testing Analysis for Vibration Modes of High-speed Train,s Door Considering the Effect of Transient Pressure Wave ZHANG Yu;WANG Yu-guo;XIN Jiang-hui;JIANG Ping 2011, 31(3): 95-98.  DOI: 10.3969/j.issn.1006-1355-2011.03.022 Abstract ( )   The relation between train door’s modes and transient pressure wave for high-speed train’s crossing is discussed. The basic theory on mode test is introduced. The basic mode of a single train’s door was obtained by hammering-impulse excitation. The developing mode of train’s door-frame system was obtained by sinusoidal frequency-scanning excitation. Combining the basic mode and the developing mode of the train’s door, its frequencies and modes of bending and torsional vibrations can be understood. With the improvement of the mode’s parameters of the train’s door, the effect of transient pressure wave in the high-speed train’s crossing can be reduced and relaxed. Related Articles | Metrics

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Testing Analysis of Torsional Vibration and Modification of Design of the Shafting of 57 000 t Bulk Carrier YU Zhao-yang;XU Xiao-xin;CHE Chi-dong 2011, 31(3): 99-103.  DOI: 10.3969/j.issn.1006-1355-2011.03.023 Abstract ( )   Using non-contact torsional vibration testing system, the torsional vibration characteristics of the shafting of 57000t bulk carrier were measured and analyzed. The results showed that the torsional vibration characteristics did not meet the predetermined requirements, and the critical section of shafting for torsional vibration was located in the intermediate shaft. Then, two different modification schemes, one by changing the length of intermediate shaft and propeller shaft and the other by increasing the diameter of the intermediate shaft, were proposed. The two modified shafting were tested respectively. The mutual comparison between the two results shows that each scheme has different effects on critical speed, torsional vibration stress, torsional vibration stress allowance and restricted speed zone. It is concluded that the scheme of increasing intermediate shaft diameter is better. This conclusion has reference values for the shafting design and follow-up building of 57000t bulk carrier. Related Articles | Metrics

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Study on Shock Isolation Control Technology of War-ship Low Frequency Isolation System with Magnetorheological Damper SHI Liang;HE Lin;ZHANG Hang;ZHU Ruo-han 2011, 31(3): 104-106.  DOI: 10.3969/j.issn.1006-1355-2011.03.024 Abstract ( )   A shock isolation control algorithm of multi-degree of freedom system is presented based on the model of magnetorheological (MR) damper. The results of simulation show that MR damper can isolate successive shocks in war-ship environment, and the displacement and acceleration of the equipment can both be restricted. Related Articles | Metrics

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Study and Application of Adaptive Control of Hybrid Vibration Isolation System of Submarine’s Power Device HU Shi-feng;ZHU Shi-jian;LOU Jing-jun;LIU Shu-yong 2011, 31(3): 107-111.  DOI: 10.3969/j.issn.1006-1355-2011.03.025 Abstract ( )   In this paper, the method of model reference adaptive control based on hybrid vibration isolation system is proposed, and the adaptive control scheme of the hybrid vibration isolation system of submarine’s power device is designed. An example of numerical simulation of the system is given. The simulation results show that the model reference adaptive control of hybrid vibration isolation system can effectively overcome the deficiency of passive vibration isolation system of submarine’s power device. Related Articles | Metrics

4.环境振动与环境声学

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Experimental Study on Standard Limits of Indoor Noise LIN Qi-li;CAO Yong;DI Guo-qing;HE Ling-jiao 2011, 31(3): 112-114.  DOI: 10.3969/j.issn.1006-1355-2011.03.026 Abstract ( )   Present room emission limits of fixed equipment noise transmitted by structures are considered incapable to predict subjective perception rationally. In this study, white noise of 31.5 ~ 500 Hz octave bands through filtration is adjusted to the sound pressure levels (SPL) of standard limits to form the original sound samples. New sound samples are produced by moderately adjusting the SPL of these 5 octave bands. Subjective annoyance tests are carried out using paired comparison method. The results indicate that, under the condition of equal A-weighted SPL or equal loudness levels, the new sound samples, whose SPL of 31.5 Hz and 63 Hz octave bands are reduced and SPL of 125 Hz and 250 Hz and 500 Hz octave bands are increased, are less annoying than the original sound samples. There is a significant correlation between SPL of 31.5 Hz octave band and the subjective annoyance rating (p < 0.01), and Pearson’s correlation coefficient is 0.925 ~ 0.951. Related Articles | Metrics

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Analysis of Sound Environment in Coastwise Area of Haihe River and Preliminary Study on its Soundscape Design and Expression ZHANG Sen;MA Hui 2011, 31(3): 115-119.  DOI: 10.3969/j.issn.1006-1355-2011.027 Abstract ( )   Haihe river, as the mother river of Tianjin, not only plays a vital role in social culture and psychology, but also provides a good place for people’s leisure and entertainment. With the advance of landscape transformation in Haihe coastwise area, creating a comfortable acoustic environment becomes an important part of the overall transformation. In this study, the sound situation of Haihe coastwise area including sound type, relationship among different sounds, sound expectation and so on, is analyzed through physical measurement and social surveys. On this base, the method of improving the acoustical environment of Haihe coastwise area and its overall soundscape design are hopefully explored. Meanwhile, a suitable expression method of soundscape design in open area like Haihe coastwise area is studied in order to build a communication platform for acoustics researchers, urban planners and the general publics. Related Articles | Metrics

6.信号处理与故障诊断

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Damage Diagnosis for Underground Arch Structure Based on Modal Strain Energy and Neural Networks FANJian-she;ZHENGFei;XU Jin-yu; 2011, 31(3): 120-124.  DOI: 10.3969/j.issn.1006-1355-2011.03.028 Abstract ( )   Underground arch structure is an important structure form of civil air defense engineering, and its damage detection is one important step for assessing the security of civil air defense engineering. Based on analysis of dynamic property of underground arch structure before and after damage, mode strain energy was proved to be sensitive to damage. The change rate of element mode strain energy was defined and taken as the damage signature. The damage location was confirmed by damage signature, and the damage extent was assured by the BP neural works. A typical air defense engineering was taken as an example, the method was verified through analyzing and discussing the calculating results of different damage. It is proved that the proposed method is correct and can detect damage in underground arch structures accurately. Related Articles | Metrics

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Application of Intrinsic Mode Function Feature Energy Method in Fault Pattern Recognition of Rolling Bearing ZHANG Tao;LU Sen-lin;ZHOU Hai-chao;SHEN Yu-gui 2011, 31(3): 125-128.  DOI: 10.3969/j.issn.1006-1355-2011.03.029 Abstract ( )   For nonlinear mapping relationship between vibration signal and state information in rolling bearing, a bearing feature vector extraction based on intrinsic mode function (IMF) feature energy in combination with support vector machine (SVM) is proposed for fault pattern recognition of bearing. The vibration signal of rolling bearing is decomposed into some IMF reflected bearing fault information by empirical mode decomposition(EMD), the energies including major information IMF are taken as eigenvectors. They are input into SVM classifier respectively for achieving fault recognition of rolling bearing. The normal state，outer race fault, inner race fault and rolling fault are simulated and tested. Results show that this method can recognize bearing fault effectively and accuracy. Related Articles | Metrics

7.减振降噪设备和器材

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Study on Several Problems of Magnetorheological Elastomer Vibration Isolators Design WANG Yu-fei;HE Lin;YANG Xue 2011, 31(3): 129-132.  DOI: 10.3969/j.issn.1006-1355-2011.03.030 Abstract ( )   Magnetorheological (MR) elastomer is a new MR material, whose rheological characteristics are controllable and invertible. It has the advantage of very fast response and low energy consuming, and becomes more and more attractive because of its wide prosperity in engineering application. Based on current research, some problems in MR elastomer isolator’s design, such as the method of developing practical MR elastomers, the material and design of magnetic circuit, etc., are systematically studied. Some important issues are put forward for further study. Related Articles | Metrics

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Suction Muffler Design of Reciprocating Compressor NIE Yong-hong;CHEMG Jun-sheng 2011, 31(3): 133-135.  DOI: 10.3969/j.issn.1006-1355-2011.03.031 Abstract ( )   The disadvantages of a compressor muffler are analyzed, and a new scheme is proposed based on the measured noise spectrum at the suction inlet of the compressor. By modifying its inner structure, the transmission loss of the new muffler at the peak frequencies of noise source is to be enhanced. The original and new mufflers are simulated by acoustic finite element method (FEM) to verify the transmission loss. Results of simulations show that the new muffler is effective at the peak frequencies of low-frequency noise source. Finally, the new muffler is tested in the compressor in order to verify its effect of noise reduction. The results show that the amplitude of noise peak at low frequency is reduced obviously and the overall noise level is reduced by 1.4dB (A). Related Articles | Metrics

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Study on Absorption Performance of Thin Micro-perforated Panel Penetrated with Copper Fiber XU Ying;REN Yu-feng;LI Chen-xi 2011, 31(3): 136-140.  DOI: 10.3969/j.issn.1006-1355-2011.03.032 Abstract ( )   In this paper, it is reported that the structure of thin micro-perforated panel (MPP) with its holes penetrated by copper fibers can extend effectively the absorption band and improve sound absorption coefficient. Thus, the sound absorption performance of the micro-perforated plate is greatly improved in the mid-and-low frequency range. The sound-absorption testing was done for the MPP samples with 100 mm and 29 mm diameters respectively, 2 mm thickness, 1mm diameter holes, 3 % perforation rate and 0.13mm diameter penetrating cooper fibers. The results show that the resonance absorption coefficient of MPP with penetration of 3 or 4 copper fibers for each hole can reach 0.99 in the frequency range of 100 Hz ~ 1 600 Hz, and its sound-absorption band can expand by 1 000 Hz when 7-9 fibers are penetrated for each hole. With increasing of the number of the fibers penetrated into each hole, the absorption band will shift to low frequency side. When 11 fibers are penetrated into each hole, the shifting magnitude can reach 464 Hz. Related Articles | Metrics

8.标准规范与评价

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Research on Noise Standards and Application for Low Speed Vehicles YANG An-jie;BI Jian-ping 2011, 31(3): 141-144.  DOI: 10.3969/j.issn.1006-1355-2011.03.033 Abstract ( )   Development and current status of China’s low-speed vehicle noise standards are researched, and the problems in use of the present standards are analyzed. It is pointed out that the standards of outside acceleration noise control for low-speed vehicle is lower, and China has not worked out the up-limit of noise level for present low-speed vehicles. It is also emphasized that promulgating more stringent mandatory standards and regulations is important for monitoring and confining the noise emission of low-speed vehicles in order to effectively control noise pollution of vehicles and protect the environment. Related Articles | Metrics

9.振动噪声测试技术

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Experimental Study on Hybrid Noise Control ZHANG Xiao-yu;YI Chui-jie 2011, 31(3): 145-148.  DOI: 10.3969/j.issn.1006-1355-2011.03.034 Abstract ( )   The traditional passive noise control with the use of sound absorption or/and insulation is effective only for the noise control in the mid and high frequency range, while the active noise control based on sound cancellation by electro-acoustical means is effective in low frequency range (<500Hz). In this paper, a hybrid noise control method is presented taking advantages of both the passive and active control approaches. In this method, the active noise control based on multi-channel FXLMS algorithm is used to reduce the low frequency noise level, meanwhile, the mid to high frequency noise level is reduced by the passive noise control. Experimental results show that the frequency bandwidth of the noise which can be controlled is extended when the hybrid control is used, and this method is effective for the broadband noise control. Related Articles | Metrics

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Noise and Vibration Analysis for Drive System of a Traction Motor LI Shuai;LIU Yan;YANG Bing;JIANG Chang-ying;ZHONG Zhi-fang 2011, 31(3): 149-152.  DOI: 10.3969/j.issn.1006-1355-2011.03.035 Abstract ( )   Using noise and vibration analysis system, the transmission system noise and vibration of a traction motor were tested, and the characteristics of the noise and vibration were analyzed. It is concluded that the noise level increases with the rotation speed increasing mainly in the frequency range near 800 Hz, and noise of MIC02 is higher than the noise of MIC01; gearbox vibration is bigger than motor vibration. This work provides a reference for noise and vibration reduction design of transmission systems of traction motors. Related Articles | Metrics

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Analysis of the Influence of Weather Conditions on Automatic Monitoring of Noise ZHANG Jin-yan;ZHANG Peng;XU Yang 2011, 31(3): 153-155.  DOI: 10.3969/j.issn.1006-1355-2011.03.036 Abstract ( )   How much can weather conditions influence the effectiveness of automatic monitoring of noise? And is it necessary to carry on synchronous meteorological monitoring for the noise automatic monitoring? In order to answer these questions, a deep analysis is required. Based on the monitoring data and related information, the correlation between sound level and wind speed is analyzed. The results indicate that wind speed should be measured simultaneously in noise automatic monitoring to ensure the reasonableness and accuracy of the data. The noise monitoring data must be modified or validated according to wind speed monitoring data. Related Articles | Metrics

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Analysis of the Methods of Weak Signal Detection LiuYuan Hong 2011, 31(3): 156-161.  Abstract ( )   Weak characteristic signal detection embedded in strong noise has been the problems of engineering applications. This paper systematically researched the methods of weak signal detection of time domain, frequency domain, time-frequency domain based on the linearity theory, and methods based on the nonlinear theory. Moreover, the basic principles and characteristics of these methods are analyzed. In the methods of correlation detection, sampling integral and digital averaging, time averaging are construed, as well as the widely employed method of frequency spectrum analysis in the frequency domain. In the method of time-frequency analysis, the STFT and wavelet transformation, which are widely applied, are analyzed. The stochastic resonance is emphasized in the method based on the nonlinear theory. Finally, it comes to the conclusion that the methods of weak signal detection based on the nonlinear theory and combined methods are the research fields in the future. Related Articles | Metrics

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Study on Video Image Testing Technique in Vibration Test HU Zhao-hui;YUAN Xiang-rong;LIU Min 2011, 31(3): 162-165.  DOI: 10.3969/j.issn.1006-1355-2011.03.038 Abstract ( )   Based on digital video technology, video image vibration measuring system is designed with the general USB digital camera and PC as its hardware. Meanwhile, the first-order modal parameters of a simply supported beam with concentrated masses applied are identified. Vibration video acquisition and image edge detection procedures are programmed in the MATLAB environment. The displacement-time curve of the beam vibration is obtained. Modal analysis is applied to determine the natural frequencies, the damping ratio and the vibration modes of the simply supported beam. The testing results show that this testing system is feasible for realization of the vibration test for low-frequency structures. Related Articles | Metrics

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Noise Reduction and Test Research of Aerodynamic Noise for Multi-blade Centrifugal Fan ZHANG Sheng-li;;XI De-ke;;LI Hua-xing;;LU Sen-lin;;ZHANG Zhong-yin; 2011, 31(3): 166-170.  DOI: 10.3969/j.issn.1006-1355-2011.03.039 Abstract ( )   In this paper, some schemes of reducing the aerodynamic noise are proposed for multi-blade centrifugal fans. Firstly, the vortex noise can be reduced mainly through the optimization of the geometric parameters of the impeller and volute and installing a rotation diffuser in the outlet of the impeller. Secondly, the discrete noise can be reduced mainly by changing the form of volute tongue. Finally, the experimental verification is carried out for the two improved fans, one is designed with optimization of inlet and outlet blade angles, and the other is installed a rotation diffuser in the outlet. The tests show that the noise of the improved fans is reduced obviously in comparison with the prototype. Related Articles | Metrics

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Study on Blanking Noise of Servo Compressor with the Counterforce Applied on Punch’s Head CHEN Li-jun;DAI Yuan-de 2011, 31(3): 171-173.  DOI: 10.3969/j.issn.1006-1355-2011.03.040 Abstract ( )   A blanking experiment was done with counterforce applied to the punch’s head from the die under a servo press machine. The noise in the blanking process was measured and compared with that in general blanking process without counterforce. Results show that the blanking noise with the counterforce applied is 3.14dB lower than the noise in the general blanking process. This blanking process can be used in industrial manufacturing. It can largely reduce the noise in production and bring an effective improvement of working conditions. Related Articles | Metrics

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Research on Volume Displacement Sensor MAO Qi-bo 2011, 31(3): 174-178.  DOI: 10.3969/j.issn.1006-1355-2011.03.041 Abstract ( )   With the example of vibrating beam of difference boundary conditions, a new method is presented for design of volume displacement sensors using shaped PVDF film on the basis of the approach of integration by parts. The PVDF sensor’s shape is independent of property of the excitation (the type, position and frequency, etc.). Furthermore, the design method proposed here does not require the information of the structural mode shapes of the structures. The boundary conditions of vibrating beam can be divided into two groups: (1) one end is clamped and the other is arbitrary; (2) both ends are pin-connected. For each group of boundary condition, the volume displacement of the beam can be measured using a certain shape of PVDF sensors. Related Articles | Metrics