Archive

18 April 2011, Volume 31 Issue 2 Previous Issue    Next Issue
---
2.振动理论与数值解法
3.运载工具振动与噪声
5.建筑振动与建筑声学
6.信号处理与故障诊断
7.减振降噪设备和器材
9.振动噪声测试技术
10.工程实践


For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

2.振动理论与数值解法

Select

Study on Flexible Structure Vibration Suppression Based on Predictive Functional Control Algorithm GOU Xin-ke;LI Da-peng 2011, 31(2): 1-3.  DOI: 10.3969/j.issn.1006-1355-2011.02.001 Abstract ( )   Taking the discrete state-space equation as prediction model, a flexible cantilever beam vibration control system is designed based on predictive-function control algorithm. The algorithm reduces the online computation and improves the real-time response ability of the system. The simulation results show that the algorithm is an effective method for vibration suppression. Related Articles | Metrics

Select

VIV and Experimental Analysis of Seismo-Acoustic Detection Sysytem LI Xiang;YAN Bing;ZHOU Sui-hua 2011, 31(2): 4-6.  DOI: 10.3969/j.issn.1006-1355-2011.02.002 Abstract ( )   Based on the principle and equation of vortex induced vibration (VIV), a vibration model of a cylindrical parts in the seismo-acoustic detection system is established, and the non-linear vibration equation is deduced and solved. The abnormal vibration in the signal is studied by comparing the experimental data. It is found that the bottom current induces the vibration of mounting pole outside the sealed cabin, so that the vibrating sensor receives this VIV signal. For this sake, the VIV suppression method, which can improve the design of detection system, is developed. Related Articles | Metrics

Select

Estimation on the Leading Lyapunov Exponent of the Response in a Typical Nonlinear System under the Bounded Noise Excitation XIE Chao-yong;LEI Hua;GAN Chun-biao 2011, 31(2): 7-11.  DOI: 10.3969/j.issn.1006-1355-2011.02.003 Abstract ( )   In this paper, the influence of the bounded noise excitation on the dynamical behaviors in a typical nonlinear oscillatory system is discussed. By using the Monte-Carlo method and small data sets method, the results of the system’s noise responses and their corresponding leading Lyapunov exponents are presented when the Holmes-type Duffing oscillator is subjected to the bounded noise excitation. It is shown that the leading Lyapunov exponent can be employed to identify chaos when the system is oriented by the determinatc harmonic excitation, from which it can be deduced that the bounded noise excitation can induce or suppress chaos. However, it is difficult to identify chaos from the sample responses and the leading Lyapunov exponents when the system is excited by bounded noise excitation only. Related Articles | Metrics

Select

Power Flow Calculation and Analysis of Vibration Isolation System Based on the Machine - Electric Similarity WU Da-de;WANG Li-bing;WANG Yu-ning 2011, 31(2): 12-16.  DOI: 10.3969/j.issn.1006-1355-2011.02.004 Abstract ( )   To investigate the dynamic transmission mechanism and control strategy of the flexible isolation system from the viewpoint of power flow is a hot topic in the field of vibration and noise control. Due to the interaction and similarity between mechanical and electrical disciplines, the Thevenin equivalent method in circuit analysis is applied to the power flow calculation in the vibration isolation system. The transmission of power flow in each coupling interface is calculated and the power flow transmission characteristic is analyzed. Program is written by means of the Matlab code for numerical simulation. The response of the system and the power flow transmissibility are simulated, and the vibration isolation system’s acceleration curve is plotted. The influence of structural parameters on power flow is systemically studied. The effects of the single-stage and multi-stage vibration isolation systems are compared. Related Articles | Metrics

Select

Study on Multi-Channel Active Noise Control with Analogue-Digital Mixed PID LI Shi-zhen;LI Gong-yu;MU Xiang-dong 2011, 31(2): 17-20.  DOI: 10.3969/j.issn.1006-1355-2011.02.005 Abstract ( )   Aiming at the characteristics of multi-harmonic frequency noise that most of electromechanical products possess, a new approach called multi-channel active noise control with analogue-digital mixed PID technique is proposed in this paper. This approach combines both multi-analogue filtering and digital phase automatic tracking PID techniques. A test of noise reduction in the duct was carried out. The results show that approach performs well for reducing multi-harmonic frequency noise in the duct. Due to the difficulty in application of the active noise control technique in 3D sound field, the sound concentrator is used to transfer the sound field from 3D into 1D in order to apply the new approach. Meanwhile, the dry-type transformer is taken as an experiment object to verify this new approach. Related Articles | Metrics

Select

Study on Natural Frequency Match in Mounting System Using Interval Response Method BAO Jian;CHENG Ai-guo;HE Zhi-cheng;WANG Zhen 2011, 31(2): 21-24.  DOI: 10.3969/j.issn.1006-1355-2011.02.006 Abstract ( )   Uncertainty of stiffness of mounting system is a challengeable problem in manufacture of vehicles. In this paper, a simulation model of the mounting system based on the response surface method is built to solve the uncertainty conditions of the mounting system. Interval analysis method is adopted to transform the uncertainty model to a determinate model. And a quadratic programming optimization method is employed in the optimization of the non-probabilistic reliability model to obtain the reliable stiffness values. The results of a real industry problem demonstrate its practicability and reliability. Related Articles | Metrics

Select

Application of Discontinuous Element in Acoustics BEM ZHANG Bo;SHEN Huo-ming;ZHI Wei 2011, 31(2): 25-28.  DOI: 10.3969/j.issn.1006-1355-2011.02.007 Abstract ( )   To solve the problem of corner point in surface in BEM, discontinuous element is employed for the discretization of Helmholtz boundary integral equation. The polar coordinate transformation in discontinuous element is presented so as to eliminate the singularity in the integration. Meanwhile, the CHIEF method and the Lagrange multiplier are applied to deal with the non-unique solutions. The value of acoustic pressures at the nodes can be acquired by solving a set of linear algebraic equations, acoustic pressure in grid points are obtained by taking the node average values or element average values. In order to demonstrate the robustness and accuracy of the proposed method, two numerical examples of sound radiation from a pulsating sphere and a cube are presented. The results calculated by discontinuous element are compared with the results determined by continuous element. The results have verified the efficiency and adaptability of the proposed method. Related Articles | Metrics

3.运载工具振动与噪声

Select

Analysis of the Main influencing Factors of Noise and Spectrum on the 2.4L type Gasoline Engine 2011, 31(2): 29-33.  DOI: 10.3969/j.issn.1006-1355-2011.02.008 Abstract ( )   The presented paper emphatically analyzed the main factors that affect the noise spectrum of engine A based on foregoing comparative analysis of noise level of engine A and B, and moreover investigate the main noise source and the measure to reduce engine noise. The results show that the main factors for noise level of engine A are ignition frequency correlative engine fundamental vibration and the radiated noise from the surface of the inlet and exhaust side of the engine. The mixture equivalence ratio and ignition timing were affecting the medium and high frequency combustion noise but not affecting the fundamental frequency. The higher the engine speed and the heavier the load, the higher the peak value of fundamental frequency. Based on aforementioned, the measures to reduce the holistic noise level of engine A are improving the structure rigidity of exhaust gas system, the control strategy of uniformization between each cylinder and decreasing vibration on crank. Related Articles | Metrics

Select

Improved Method of NVH Transfer Path Analysis and Application Cheng Wang;Liang Tianye;Chuanxue Song;Wenku Shi 2011, 31(2): 34-37.  DOI: 10.3969/j.issn.1006-1355-2011.02.009 Abstract ( )   Aiming at the problem of testing time consuming and low accuracy of transfer function estimation in the traditional TPA method, an improved TPA method is presented based on a new transfer function estimation method. Adopting the improved TPA method, the three-point suspension of powertrain was analyzed and a contrast simulation experiment was made. Since the new transfer function estimation method can eliminate the influence of the random noise, the estimation accuracy is enhanced. The improved TPA method elides the car body impendence testing and reduces the testing time. The simulation results show that the improved TPA method is viable. Related Articles | Metrics

Select

Input Shaper Applied to Anti-swing Control of Cherry Picker Ying-Long JING 2011, 31(2): 38-42.  DOI: 10.3969/j.issn.1006-1355-2011.02.010 Abstract ( )   To design EI, ZV and ZVD input shaper in order to reduce vibration of work platform of cherry picker on movement and the residual vibration. To derive mathematical model, dynamic characteristic equations are obtained and the pulse amplitude and time of input shaper was calculated. Comparing swing angle of work platform with input shaper and without, the results show that the EI, ZV and ZVD input shaper are effective in reducing the system vibration on movement and the residual vibration, and EI input shaper is best. Related Articles | Metrics

Select

Apply of vehicle detection based on video in traffic noise prediction Huan Hong-Jiang 2011, 31(2): 43-47.  DOI: 10.3969/j.issn.1006-1355-2011.02.011 Abstract ( )   Now the FHWA model used in traffic noise prediction get the number and type of vehicles by artificial way, the labor cost is high and the statistical value often not very accuracy. By introduced the connection level of changed pixels on the virtual detection line, a new vehicle detection algorithm proposed was based on the theory of Medium measurement logic and the information of the length of vehicle. Using the technologies of Image Processing and pattern recognition, the algorithm can get the number and type of vehicles automatic, the result can combine with FHWA model effectively. The experiment results proved the algorithm achieves good performance, provided accurate traffic volume data for the FHWA model. Related Articles | Metrics

Select

Analysis of Panel Contribution to Vehicle Interior Noise LIU Dong-ming;FANG Jian;ZHAO Jing-yi;LU Yu-dong 2011, 31(2): 48-51.  DOI: 10.3969/j.issn.1006-1355-2011.02.012 Abstract ( )   This article discusses the method to analyze the acoustic contribution of body’s panels to vehicle’s interior noise. In the experiment, the vector sum of the product of sound-source intensity and acoustic transfer function is used to compose the sound pressure contribution of the panels. The source intensity of a panel is derived from the product of normal velocity of the surface and its area. Acoustic transfer function is measured via reciprocity principle. FEA calculation is done based on a model with the boundary condition and load condition of the foregoing experiment. Finally, test synthesized results, FEA results and measured data are compared one another. Related Articles | Metrics

Select

Slipway noise control and prediction of noise reduction LI Zheng-guang;DI Guo-qing;SHI Xiang;ZHENG Yue 2011, 31(2): 52-55.  DOI: 10.3969/j.issn.1006-1355-2011.02.013 Abstract ( )   Some measures for noise control of slipway and prediction of noise reduction effect are proposed. An actual case of slipway noise control is taken as an example. According to the characteristic of the slipway noise, a noise source model is built, and the noise reduction effect of these measures for noise control is predicted. The results show that the comprehensive treatment, including sound source control, sound transmission control and production management, is necessary to control the noise. In addition to considering the noise reduction effect, engineering feasibility, cost as well as social factors also need to be considered in building the sound barriers. This work provides a reference for slipway noise control and prediction. Related Articles | Metrics

Select

Control on Steering Wheel Shimmy of the Car at High Speed ZHANG Yong-li;XU Xiang;WU Yun 2011, 31(2): 56-58.  DOI: 10.3969/j.issn.1006-1355-2011.02.014 Abstract ( )   The factors which affect steering wheel shimmy are briefly introduced in this paper. The causes of steering wheel shimmy are investigated by road reappearance test. Frequency spectrum analysis, coherence analysis and order analysis are applied to locate some defective parts, which are optimized and validated later on. The results show that the steering wheel shimmy is reduced effectively. Related Articles | Metrics

Select

Numerical Analysis and Optimization of Automotive Exhaust Muffler’s Acoustic Characteristics GONG Jian-guo;JIN Tao;MA Yu-shan;CUI Wei-sheng 2011, 31(2): 59-62.  DOI: 10.3969/j.issn.1006-1355-2011.02.015 Abstract ( )   Exhaust muffler’s sound field is calculated with Sysnoise software. Sound pressure distribution and transmission loss plot are obtained. Noise elimination structure is improved, and a diaphragm and two perforated pipes are set inside the muffler. The results show that the acoustic wave with low frequency propagates in a form of plane wave, while acoustic wave with high frequency propagates in a form of high-order harmonic wave. Compared with the original muffler, the improved muffler’s transmission loss increases by more than 20 dB in 600-1200 Hz, 1700-1800 Hz and 2700-2800 Hz frequency ranges. And the improved muffler’s transmission loss increases by 19.8 dB in average in 20-3000 Hz frequency range. Thus, the improved muffler’s noise elimination effect is good. Related Articles | Metrics

5.建筑振动与建筑声学

Select

Statistical Energy Analysis Approach in the Noise of LI Xin;PENG You-duo peng;Li-tao WU;Wei-hua XIE 2011, 31(2): 63-67.  DOI: 10.3969/j.issn.1006-1355-2011.02.016 Abstract ( )   The sound field of hydraulic hoist chamber with five sides sealed is studied in this paper. The acoustic models of the pump station chamber, walls, doors and the main chamber are established by applying the statistical energy analysis (SEA) theory. The loss factors, modal density and other related parameters of the models are determined and analyzed. The sound insulation and noise reduction characteristics of the walls and the doors are analyzed. The noise of hydraulic hoist chamber and driver’s console is predicted. This work has significance and guidance for the hydraulic hoist chamber’s environmental noise control. Related Articles | Metrics

Select

Application of Sound insulation-ventilation window in Expo 2010 WU Jian-chun;ZHANG Ming-fa;YANG Rong-ping;ZHU Zi-gen 2011, 31(2): 68-70.  DOI: 10.3969/j.issn.1006-1355-2011.02.017 Abstract ( )   The acoustic characteristic and practicability of sound-insulation ventilation window are analyzed. A case study of a typical sound-insulation ventilation window in Shanghai Expo 2010 is introduced. And its performance is proved excellent by the worksite testing. Related Articles | Metrics

Select

Design of Closed-Cell Aluminum Foam Sound Barriers LIANG Li-si;YAO Guang-chun;MU Yong-liang;HUA Zhong-sheng 2011, 31(2): 71-74.  DOI: 10.3969/j.issn.1006-1355-2011.02.018 Abstract ( )   To reduce noise pollution of expressway and design better-performance sound barriers, an acoustic resonance type sound barrier is designed using closed-cell aluminum foam. The noise spectrum analyzer is used to measure the noise pollution. The sound absorption coefficient is measured using stationary-wave method. The closed-cell aluminum foam panel with 0.3g/cm3 mass density, 10mm thickness and 3% perforation rate are used for the noise barrier. A 30mm thick cavity is designed on its back. The results of measurement show that the main sound absorption frequency range is from 300 to 400Hz, the sound absorption coefficient can reach 60%-90% for the noise frequencies lower than 500Hz. Related Articles | Metrics

Select

Noise Reduction and Sound Insulation of Residential Building in the Vicinity of Capital International Airport ZHANG Qing;GuoHua- YAN;Kuo FANG 2011, 31(2): 75-79.  DOI: 10.3969/j.issn.1006-1355-2011.02.019 Abstract ( )   In recent years, complaints about aircraft noise have been increasing. In this paper, the measures for noise insulation and reduction of residential buildings in the vicinity of airport is reviewed and discussed. Aircraft noise of the Capital Airport and the characteristic of noise around the residential buildings near the airports are monitored. The weighted equivalent continuous perceive noise level and the day-and-night equivalent sound level are applied together to assess the effect of aircraft noise. Some standards and measures for sound insulation of the buildings around airports are also suggested. Taking a residential building near the capital airport as an example for sound insulation and reduction, the noise level outside and inside the building is measured in 13 seconds after airplane taking off, and the sound insulation volume inside the building is also tested. The results show that sound insulation measures for residential buildings can provide a comfortable, quiet, intimate acoustic environment. Related Articles | Metrics

Select

Detecting and Extracting Vibration Disturbing in IMU Outside Calibration LIU Gang;YANG Jie;WANG Li-xin;GAO Jiang;WANG Xiao-mei 2011, 31(2): 80-83.  DOI: 10.3969/j.issn.1006-1355-2011.02.020 Abstract ( )   IMU (Inertial Measurement Unit) is often disturbed by the ground vibration when it is calibrated outside. This vibration disturbing will have great influence on the calibrating precision of the IMU. In this paper, the mathematical model for the vibration signal is established. Then, based on the difference of singularity of vibration signal and noise signal, the output signal of the IMU is analyzed by using wavelet modulus maximum method. Finally, the algorithm to restrain the noise disturbance and to extract the vibration signal is deduced. Simulation shows that this arithmetic has very good ability to detect the vibration disturbing. Related Articles | Metrics

6.信号处理与故障诊断

Select

Damage Identification of Structure Based on Lifting Wavelet Packet and Fuzzy Pattern Recognition Tan Dong-Mei;QU Wei-lian 2011, 31(2): 84-88.  DOI: 10.3969/j.issn.1006-1355-2011.02.021 Abstract ( )   The damage identification method of truss structure based on lifting wavelet packet analysis and fuzzy pattern recognition is developed according to damage feature of the structure. Firstly, the vibration signal is decomposed using lifting wavelet packet (WP) analysis, and then the corresponding characteristic vector of damage identification is established by the lifting WP component energy, which can be used as the subset of fuzzy pattern recognition. Finally, the damage is detected based on fuzzy C-means clustering and the nearest neighbor algorithm, and the effect of noise on these algorithm is also studied. In order to verify the proposed method, the numerical simulation of a two-story truss structure model is carried out. The results show that the proposed method can be effectively used to identify the damage of structures. Related Articles | Metrics

Select

Fault Pattern Recognition of Rolling Bearing Based on EMD-SVD Model and SVM WU Hu-Sheng;Jian-Xin LV;Lai-Hong LAI;Lu-Shan WU;Yu-Rong ZHU 2011, 31(2): 89-93.  DOI: 10.3969/j.issn.1006-1355-2011.02.022 Abstract ( )   According to the non-stationarity characteristics of the vibration signals from rolling bearing and the difficulty for obtaining enough fault samples, a comprehensive fault diagnosis method based on Empirical Mode Decomposition (EMD)，Singularity Value Decomposition (SVD), Renyi-entropy and Support Sector Machine (SVM) is proposed. Firstly, the denoised vibration signals are decomposed into a finite number of Intrinsic Mode Functions (IMF). Secondly, some IMF components are selected according to the criterion of mutual correlation coefficient between IMF components and denoised signal. Thirdly, the phase space of the selected IMF components is reconstructed so as to obtain the attractor orbit matrix. Fourthly, with the SVD method, singular value sequences are obtained, and then Renyi-entropies of these sequences are calculated as faulty eigenvector. Finally, the eigenvector serves as input of SVM classifier so that the faults of rolling bearing are recognized. Practical rolling bearing experiment data is used to verify this method, and the diagnosis results and comparative tests fully validate its effectiveness and generalization ability. Related Articles | Metrics

Select

Application of Improved BP Neural Network in Fault Diagnosis of Fans MI Jiang;JI Guo-yi 2011, 31(2): 94-98.  DOI: 10.3969/j.issn.1006-1355-2011.02.023 Abstract ( )   An improved BP neural network with the methods of momentum and adaptive learning rate is applied to build the fault diagnosis system of the fans. In the process of training, standard training samples and samples with white noise are employed to train the neural network so that the neural network has some ability of fault tolerance. Results of the simulation and the fault diagnosis of a fan show that the improved BP neural network needs less training times, the learning efficiency is raised, and the phenomenon of trapping in the local minimum for the network is effectively repressed. This method is effective for the fault diagnosis of fans. Related Articles | Metrics

Select

Fault Diagnosis Method for Aero-Engine Rotor System Based on the Phase Plane Similarity XIAO Qiang;LI Xue-ren;DU Jun 2011, 31(2): 99-102.  DOI: 10.3969/j.issn.1006-1355-2011.02.024 Abstract ( )   Aiming at the problem that vibration signal is easily affected by noises in early fault identification, an aero-engine rotor system fault diagnosis method is presented based on the similarity of phase planes. Fault types are identified by calculating the similarity of phase plane plots based on the overall vibration signal parameters in various ranges and states. Simulation shows that the method proposed can efficiently resist the noises and diagnose the faults with high speed and precision, and thus has significance in practical application. Related Articles | Metrics

7.减振降噪设备和器材

Select

Modelling and Experimental on MRF Damper Force of Tracked Vehicle ZHANG Jian;ZHANG Jin-qiu;QI Yun-guang;ZHOU Xiao;ZHANG Lei 2011, 31(2): 103-106.  DOI: 10.3969/j.issn.1006-1355-2011.02.025 Abstract ( )   An MRFD force model is established for damper force characteristic investigation through theoretical analysis. Force characteristic of MRFD was studied experimentally in self-made testing equipment. The relationships between force and displacement, force and current, force and velocity were tested. The damper force of MRFD for a given velocity is predicted by the theoretical model. The experiment results show that the theoretical model and the experimental data are in agreement, and the damping coefficient can reach 3.5. Related Articles | Metrics

Select

Study on Energy Dissipation Characteristics of YGG Type Steel Wire Rope Shock Isolator Excited by Shock Loads DU Jian-guo;FENG Jin-ji;XIE Qing-liang;HE Yong-sheng 2011, 31(2): 107-114.  DOI: 10.3969/j.issn.1006-1355-2011.02.026 Abstract ( )   In this paper, the model of YGG type steel wire rope shock-isolation system with single degree of freedom is introduced, and the energy response equations are derived. By solving the equations, the transfer, dissipation and distribution of the energy are obtained when the system is excited by shock loads. The principle of passive shock isolation of YGG type steel wire rope shock-isolation system is revealed from the viewpoint of energy. Based on the analysis of the results, the influence of input total energy, pre-compression, weight quota and axial force on the energy distribution and the energy dissipation characteristics of the steel wire rope shock-isolators is discussed. The axial and lateral energy-dissipation abilities of YGG-8kN steel wire rope shock-isolator are obtained. This work provides a reference for theoretical study on the entire shock isolation, efficiency evaluation, technique and design study in explosion and shock environment. Related Articles | Metrics

Select

Application of Dynamic Vibration Absorber in Vibration Control of Power Assembly LIU Jian-ya;LI Shun-ming;JIANG Jian-zhong;ZHUANG Yan;SUN Bo;LU Zhi-yao 2011, 31(2): 115-118.  DOI: 10.3969/j.issn.1006-1355-2011.02.027 Abstract ( )   To reduce the excessive vibration of power assembly, the vehicle test and local modal analysis of a minibus have been carried out. The results of analysis prove that the excitation frequency from the engine is close to the natural frequency of the vibration system composed of the corbel and its mounting. Based on the design theory of dynamic vibration absorber (DVA), a damping DVA has been designed and assembled in the power assembly. The vehicle test results show that the DVA can effectively control the vibration of the power assembly. The theoretical analysis and testing methods provide some reference for similar engineering. Related Articles | Metrics

Select

Research of Fractured of a Muffler WANG Xiao-yan; LI Zhi-yuan 2011, 31(2): 119-122.  DOI: 10.3969/j.issn.1006-1355-2011.02.028 Abstract ( )   Aiming at the problem of fatigue fracture at the welding between muffler cylinder and exhaust pipe, the CAE quantitative analysis method and modal analysis technique are used to analyze the cracked muffler. An improvement scheme of letting the exhaust pipe pass through the muffler cylinder is proposed. Meanwhile the theoretical and experimental modal analyses are done for the muffler before and after the improvement. Results of analysis show that the improvement measures are reasonable, and the reliability of the muffler is raised. Related Articles | Metrics

Select

Study on Absorption Property of Porous Sound-Absorbing Materials LIU Peng-Hui;YANG Yi-qian;YAO Jing-chuan 2011, 31(2): 123-126.  DOI: 10.3969/j.issn.1006-1355-2011.02.029 Abstract ( )   Porous sound-absorbing materials are widely used because of its high sound absorption coefficient and wide absorption frequency range. In this paper, a model of sound absorption materials is adopted, and the design parameters are computed. The influence of porosity, diameter of holes, thickness and structure of the material on its sound-absorbing property is analyzed. This work provides a reference for the development of new sound-absorbing material. Related Articles | Metrics

Select

Application of MR Damper in Structural Vibration Control DU Lin-ping;SUN Shu-min 2011, 31(2): 127-130.  DOI: 10.3969/j.issn.1006-1355-2011.02.030 Abstract ( )   MR damper is an ideal semi-active control device. In this paper, the applications of MR damper to structural vibration control in construction engineering, bridge engineering, mechanical engineering, naval architecture and ocean engineering, aeronautical engineering, and other engineering fields are summarized. Related Articles | Metrics

Select

The Application of Complex Casting Board of Sound Absorption and Barrier in Road Noise Barrier NI Rong 2011, 31(2): 131-133.  DOI: 10.3969/j.issn.1006-1355-2011.02.031 Abstract ( )   The composite casting board of sound absorption and isolation is made up of a sound-absorption casting board as the panel and a metal board as the backplane with cavity in the middle. In the manufacture of this board, a polyurethane board is taken as a carrier. Then, it is coated by mixed cream including some basic components such as casting powder, additives, water and gelatin. After vibrational consolidation process, this board is solicited in the natural environment. Taking the composite casting board of sound absorption and isolation, which consists of 30mm thick acoustical casting board, 69mm thick cavity and 1mm thick galvanized steel sheets, its noise reduction coefficient (NRC) can reach 0.62, and the air-acoustic weighted isolation Rw can reach 28dB. The research shows that if this kind of board is used in road noise barrier project, the noise reduction volume will reach 6.1 dB in the sound shadowing region of a 2.8m high noise barrier. Related Articles | Metrics

9.振动噪声测试技术

Select

Discussion on Aircraft Noise Evaluation Parameters in Airport and Their Limited Values XIAO Hui-hui;WANG Chao ;XU Xiao-hao 2011, 31(2): 134-137.  DOI: 10.3969/j.issn.1006-1355-2011.02.032 Abstract ( )   The shortcomings of current airport noise evaluation parameters, which include weighted equivalent continuous perceived noise level (WECPNL), are analyzed. According to the above analysis, equivalent sound level Leq and sound exposure level (SEL) are proposed as the new airport noise evaluation parameters. Annoyance and sleep disturbance caused by the aircraft noise are analyzed in detail. And the limitation values of corresponding noise evaluation parameters are suggested. Related Articles | Metrics

Select

Prediction and Assessment of the Environmental Noise in Xiuzhou District of Jiaxing City SHEN Hong-xia;HU Li-fan;TAO Yan-ying 2011, 31(2): 138-141.  DOI: 10.3969/j.issn.1006-1355-2011.02.033 Abstract ( )   Fuzzy clustering method is used to analyze the environmental noise quality of Xiuzhou district and determine the overall level of noise pollution of this region. According to comprehensive analysis of the present road traffic situation and the city planning, the road traffic noise pollution in 2011, 2015 and 2020 years is quantitatively predicted by means of the simplified FHWA model. This paper may provide references for the environment quality protection of Xiuzhou district and prediction of traffic noise pollution levels of some other areas. Related Articles | Metrics

Select

Preliminary Study on “Noise Island” Topographic Distribution Method Applied in Urban Region Noise Monitoring Points Optimization ZHAO Li-min;LI Ya-dan;;WANG Zheng;WANG Shuang-wei 2011, 31(2): 142-146.  DOI: 10.3969/j.issn.1006-1355-2011.02.034 Abstract ( )   Environmental noise pollution is influencing our daily life seriously. The regional noise pollution can be evaluated by using noise monitoring point optimization method. It has an important significance for planning and management of the environment. At present, there are some limitations for application of the environmental noise monitoring point optimization methods to urban regions in China. In this paper, the urban “Noise Island” concept is proposed. The environmental noise monitoring point optimization of an area in Changchun is carried out as an example applying the “Noise Island” topographic distribution method, with integrated neural network as the main technical means. The noise monitoring point is selected by using the “terrain” of the “Noise Island” for the first time. On this basis，the point selection and optimization rules of the best noise monitoring point distribution are found. Related Articles | Metrics

Select

Study on Numerical Prediction and Experimental Measurement of Acoustic Performance of Silencers in Medium Frequency Range LI Zi-qiang;JI Zhen-lin;ZHANG Tie-zhu;WU Yao 2011, 31(2): 147-150.  DOI: 10.3969/j.issn.1006-1355-2011.02.035 Abstract ( )   ( College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China ) Abstract : The finite element method is used to calculate the internal sound field of a silencer, the mode waves are decomposed based on the acoustic mode theory, and then the transmission loss is determined. Based on the same theory, the transmission loss is measured through wave decomposition method with multi-sensors. It is found that results of the experimental measurement agree well with those of the numerical predictions. The effective frequency range for prediction and measurement of transmission loss are both extended beyond the cut-off frequency. Related Articles | Metrics

Select

Application of Adaptive Filtering to Noise Measurements of Automotive Alternators NIE Yong-hong;CHENG Jun-sheng 2011, 31(2): 151-155.  DOI: 10.3969/j.issn.1006-1355-2011.02.036 Abstract ( )   The setup for noise measurement of automotive’s alternators and its characteristics are introduced. Adaptive filtering is applied to the separation of alternator’s noise from the background noise of the test bench, and is compared with independent component analysis (ICA). The experimental results show that the adaptive filtering can separate the measured noise effectively. And this method can be used to carry out noise measurements of automotive’s alternators without rebuilding the test bench. Related Articles | Metrics

Select

Measurement and Spectrum Analysis of Background Noise of Aeroacoustic Wind Tunnel GU Guang-Wu;ZHU Bo 2011, 31(2): 156-158.  DOI: 10.3969/j.issn.1006-1355-2011.02.037 Abstract ( )   It is necessary to measure and analyze the background noise of aero-acoustic wind tunnel in order to reduce its sound pressure level (SPL). In this paper, the measurement scheme and frequency spectrum analysis of a 0.55m×0.4m aero-acoustic wind tunnel are introduced. According to the acquired data, the power spectrum density is obtained by means of the average periodic diagrams, and the result is comprehensively analyzed. The result of measurement shows that the SPL of the background noise is 78.15dB when the wind speed in the open-jet test sections is 80m/s. Related Articles | Metrics

Select

Study on Vibration Real-Time Monitoring Technique of Aero-Engine in Flight Test ZHANG Qun-yan;ZHAO Shu-yuan;LI Fei-xing 2011, 31(2): 159-162.  DOI: 10.3969/j.issn.1006-1355-2011.02.038 Abstract ( )   Aiming at the requirement of an aero-engine flight-test, a project of vibration real-time monitoring was designed. Then the vibration real-time monitoring device based on the project was designed and collocated. This device and the original equipment were applied together to realize the aero-engine vibration real-time monitoring in flight-test. The application shows that design of the project and scheme of the device can meet the requirement of the flight-test. Related Articles | Metrics

Select

Inverse Method of Microphone Array and Aircraft Noise Source Identification MA Jun-hui;QIAO Wei-yang;TAN Hong-chuan;ZHAO Lei 2011, 31(2): 163-169.  DOI: 10.3969/j.issn.1006-1355-2011.02.039 Abstract ( )   In order to develop and improve the technique of identification and measurement of aircraft noise source, and to understand the essential properties of the noise source deeply, a large planar microphone array for the landing process of large civil aircraft has been developed. This plane array is composed by 104 microphones whose positions in the plane are determined by the computer aided optimization design. Meanwhile, the spectrum characteristics of the array have been tested by means of numerical simulation. The plane array has been used to measure the noise sources of 20 landing aircrafts in the Xi’an Xianyang International Airport. In the experiment, a noise source identification and measurement system for large civil aircraft has been built and developed, and the microphone array technique and its data processing software also have been verified. Related Articles | Metrics

10.工程实践

Select

Research and Application of Tubing Collision Noise Control Technology DU Bing-guo 2011, 31(2): 170-173.  DOI: 10.3969/j.issn.1006-1355-2011.02.040 Abstract ( )   The tubing collision noise is the primary noise source in the tubing plant, which does great harm to people. There is no better solution at home and abroad. By analyzing the pipe rolling characteristics of the tubing on the pipe bridge, this paper finds the scientific evidence of the pipe bridge slope design, identify the origin and law of tubing collision noise. Based on this theory as guidance, the tubing collision protection device has been developed, which designs the forcible constraint of tubing rolling on the pipe bridge , avoiding the collision of tubing with each other, while positioning of tubing forcible arrangement has been realized. The tubing collision noise has been successful solved. Related Articles | Metrics