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18 October 2015, Volume 35 Issue 5 Previous Issue    Next Issue

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Research Advances of Noise Sources Identification for Engineering Machinery 2015, 35(5): 1-15.  DOI: 10.3969/j.issn.1006-1335.2015.05.001 Abstract ( )   PDF (2467KB) ( )   Related Articles | Metrics

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Numerical Simulation of the Steady Vibration Response Induced by Interior Flow of Heat Exchangers 2015, 35(5): 16-20.  DOI: 10.3969/j.issn.1006-1335.2015.05.002 Abstract ( )   PDF (1603KB) ( )   the characteristics of flow induced vibration in the heat transfer has been discussed in this paper, it is mainly about study of the vibration induced by the inner flow of the heat transfer , which makes the whole heat exchanger shake, and evaluation of the reaction of the heat exchanger. Fluid-structure sequential coupling principle is taken use of, by applying the commercial software Fluent to calculate the distribution of the surface pressure, then MATLAB is adopted to deal with the output fluid pressure data, the nonlinear factors are ignored for modeling the structure, the harmonic excitation, which is get from the Fluent, then is loaded for computing the steady response reaction force of the heat exchanger. Related Articles | Metrics

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Analysis of the Anti-shock Performance for Flanged Hydraulic Couplings 2015, 35(5): 21-24.  DOI: 10.3969/j.issn.1006-1335.2015.05.003 Abstract ( )   PDF (1306KB) ( )   Related Articles | Metrics

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Multi-line Spectral Control Based on Reciprocal Decoupling in Hybrid Vibration Isolation Systems 2015, 35(5): 25-29.  DOI: 10.3969/j.issn.1006-1335.2015.05.004 Abstract ( )   PDF (1492KB) ( )   Related Articles | Metrics

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Flap/Lead-lag Aeroelastic Stability Analysis for Wind Turbine Blades 2015, 35(5): 30-34.  DOI: 10.3969/j.issn.1006-1335.2015.05.005 Abstract ( )   PDF (1623KB) ( )   The nonlinear partial differential equations that govern the coupled flap-lead/lag vibration of wind turbine blades are established based on the Euler-Bernoulli beam theory and the Kelvin-Voigt theory of composite materials. By decomposing blade displacement into static and dynamic displacements, the nonlinear governing equations are linearized to the linear equations of the dynamic displacement, and then the characteristic equation of the coupled vibration is obtained. The Galerkin method that is based on the method of weighted residuals is employed to solve the characteristic equation and analyze the aeroelastic stability of blades. The influence of wind speed, setting angle, coupling and material damping on the aeroelastic stability and nonlinear self-excited oscillation of the blade is discussed. Results show that the coupling between flapwise and edgewise motion can be used to improve the aeroelastic stability of the blade, but it can bring about instability if the coupling is too strong. Related Articles | Metrics

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Study on the Composite Sound Absorber Made up of Porous Materials and MPP 2015, 35(5): 35-38.  DOI: 10.3969/j.issn.1006-1335.2015.05.006 Abstract ( )   PDF (1284KB) ( )   s paper studied how to widen the sound absorption bandwidth of MPP combined with the porous materials. The MPP was chosen to absorb the low frequency noise, while the porous materials were selected to enhance the sound absorption in the middle and high frequency range. The calculation and measurement of the sound absorption coefficient were also presented. The experimental results had a good agreement with the predicted results. The comparison indicated that when the porous material was put in front of the MPP and there was an air layer between them, the sound absorbing characteristics of MPP can be greatly improved. Related Articles | Metrics

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Energy Dissipation Analysis of Micromechanical Resonators with Variable Anchor Structures 2015, 35(5): 39-42.  DOI: 10.3969/j.issn.1006-1335.2015.05.007 Abstract ( )   PDF (1238KB) ( )   Related Articles | Metrics

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Dynamic Similarity Relations of Straight Blades Considering Dynamic Softening Effects 2015, 35(5): 43-47.  DOI: 10.3969/j.issn.1006-1335.2015.05.008 Abstract ( )   PDF (1151KB) ( )   Related Articles | Metrics

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Design of Numerical Simulation System of Ball-type Automatic Balancers 2015, 35(5): 48-52.  DOI: 10.3969/j.issn.1006-1335.2015.05.009 Abstract ( )   PDF (1447KB) ( )   Related Articles | Metrics

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Optimal Bounded Control of Large Random Vibration Responses in Nonlinear Systems 2015, 35(5): 53-55.  DOI: 10.3969/j.issn.1006-1335.2015.05.010 Abstract ( )   PDF (1271KB) ( )   The optimal bounded minmax control for random vibration of nonlinear systems is studied. A variable is used for rescaling system responses and a high-order power polynomial is used as the cost function in performance index for magnifying large vibration responses. The optimal bounded minmax control problem for nonlinear random vibration is expressed by the transformed differential equation and performance index of the system. Then the HJB equation is derived based on the random dynamical programming principle. The optimal bounded semi-continuous and switching control laws are obtained by solving the equation with considering the control boundness. Numerical results show that the proposed control can effectively suppress the nonlinear random vibration. The control effectivenesses are compared for different variable values, control bounds, semi-continuous and switching controls. Related Articles | Metrics

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Vibration Analysis and Control for Luxury Yachts 2015, 35(5): 56-59.  DOI: 10.3969/j.issn.1006-1335.2015.05.011 Abstract ( )   PDF (1268KB) ( )   Related Articles | Metrics

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Performance Analysis and Test of a Spacecraft Adaptive Dynamic Vibration Absorber 2015, 35(5): 60-64.  DOI: 10.3969/j.issn.1006-1335.2015.05.012 Abstract ( )   PDF (1652KB) ( )   Adaptive dynamic vibration absorber (ADVA) has been proved effective to the rotating parts on spacecraft. However, mechanical ADVA is too large and heavy to attach on satellite. In this article, one type of electromagnetic ADVA is introduced and the mathematic model of it is built. Also, performance analysis and simulation was applied. Furthermore, by making prototype, the frequency changing ability of the ADVA was tested. The experiment result showed that the frequency changing system can provide up to 4000N/m of stiffness, which means 45Hz for the ADVA. It was also showed that the ADVA was able to decrease the vibration of the main structure and the adjust speed and accuracy can meet the requirement of spacecraft application. Related Articles | Metrics

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Study on the Modeling Methods of Honeycomb Sandwich Panels Based on Fairing Vibroacoustic Experiments 2015, 35(5): 65-68.  DOI: 10.3969/j.issn.1006-1335.2015.05.013 Abstract ( )   PDF (1077KB) ( )   Related Articles | Metrics

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Control of Semi-active Suspension of Vehicles Based on Parameter Sensitivity Feedback 2015, 35(5): 69-72.  DOI: 10.3969/j.issn.1006-1335.2015.05.014 Abstract ( )   PDF (1300KB) ( )   In order to improve the adaptation of operation parameters to suspension controller, the parameter sensitivity was introduced to suspension control system to lower parameter sensitivity, which was different to the adaptive and self-tuning methods. The control system was composed of state feedback and sensitivity feedback. The controller was designed under vehicle and operation parameters commonly used with the method in this paper, and compared with LQR controller. The research shows that the gains of body acceleration and tire deflection obtained by parameter sensitivity feedback decreases by 6-8dB compared with LQR, and the suspension deflections gotten by two methods are closed. In addition, parameter sensitivity feedback has better robustness than LQR in the stronger excitation, higher velocity and small load case. Related Articles | Metrics

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Vibration Characteristic Analysis and Hanger Location Optimization of Bus Exhaust Systems 2015, 35(5): 73-76.  DOI: 10.3969/j.issn.1006-1335.2015.05.015 Abstract ( )   PDF (1216KB) ( )   The noise and virbration of exhaust has a great impact on NVH performance of vehicles,good hanger locations and stiffness of exhaust system can effectively reduce the vibration energy transfer between exhaust system and vehicle body.The software of Hyperworks is applied to creat finite element model of the Extended-Range electric bus’s exhaust system, Based on finite element theory ,the modal analysis and static equilibrium analysis were completed. The hanger’s displacement is calculated by static equilibrium analysis,the natural frequency and modal shape are obtained by modal analysis, The theoretical optimal solution of hanger location is obtained by applying the average driving DOF displacement(ADDOFD) theory , it providing a effective technical basis for the selection of hanger stiffness and location by assessing the results of those analysis. Related Articles | Metrics

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Decoupling Optimization of an Automotive Powertrain Mount System Based on Genetic Algorithm 2015, 35(5): 77-81.  DOI: 10.3969/j.issn.1006-1335.2015.05.016 Abstract ( )   PDF (1113KB) ( )   To avoid the local optimal solution of the automotive powertrain system solved by traditional optimization algorithm, the system is optimized by genetic algorithm. After deep analysis the principle of selection of design variables, the extraction of constraint functions and the selection of the objective function, taking the stiffness parameters of the mounting system as the design variable, the scope and interval of natural frequency as the constraint function, and the decoupling rate of the six-degrees-freedom as the energy decoupling and the transmission rate, powertrain mounting system was optimized by genetic algorithm on MATLAB. The powertrain mounting system of a vehicle was optimized by the system which developed based on genetic algorithm to optimize powertrain mounting system. Optimization results show that the system of the distribution of the natural frequency and decoupling rate is greatly improved, and the efficiency and accuracy are greatly improvement. Related Articles | Metrics

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Seal Performance Control of Automobile Doors and Wind Noise Reduction of Vehicles 2015, 35(5): 82-86.  DOI: 10.3969/j.issn.1006-1335.2015.05.017 Abstract ( )   PDF (1275KB) ( )   Abstract：Seal performance of automobile door is one of the important effects for vehicle wind noise level, analysed seal mechanism of main automobile door components, and presented the relevant methods of leak control. For back door “leak noise” of one SUV automobile, the seal optimization of door is carried out to eliminate the abnormal wind noise, achieved improvement targets on both subjective evaluation and objective testing. Related Articles | Metrics

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Analysis and Control of Cab Structure-borne Noise of Heavy-duty Commercial Vehicles 2015, 35(5): 87-90.  DOI: 10.3969/j.issn.1006-1335.2015.05.018 Abstract ( )   PDF (1529KB) ( )   There are mainly low and medium frequency structural noises in operating heavy-duty commercial vehicle cabs. In order to identify the major contributing components that make such structural noises, this article adopts a finite element model that assimilates a heavy-duty commercial vehicle. By way of experimental modality and simulation modality benchmarking, precision of the finite model is guaranteed. The model is tested and through acoustic transmission path analysis, it has been proved that mental plate is the material cause for the structural noises in the cab. After an asphalt rubber slab is attached to the surface of the mental plate, the noises in the cab lowered about 1~1.5 dB (A) through simulation experiment and real vehicle test. It is proved that the analysis result method is correct and that the improvement measure is effective. Related Articles | Metrics

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Analysis of Interior Noise and Vibration of HEV Engines in Power Switching Process wu saisai 2015, 35(5): 91-96.  DOI: 10.3969/j.issn.1006-1335.2015.05.019 Abstract ( )   PDF (1812KB) ( )   For the study of the vibration and noise of one hybrid car in a power switching process ,we test the vibration acceleration in two driving position's floor , skipper binaural noise, deputy driver's right ear and driving back’s right ear noise, engine speed and battery power (SOC). Data processing adopts wavelet packet transform、time domain and frequency domain analysis method to analyse the vibration and noise of the car in a switching process. The test results show that, the noise and vibration in power switching time are presented clearly unsteady characteristics and the energy concentrates in the low frequency range and has a obvious difference between the peak of steady speed and pure electric mode ；there is a relationship between obvious strengthened vibration peak appeared in 558Hz and the fast rising torque of start motor drive engine starting ；There will be noise amplitude discrepancy in different position of the car, it may be associated with the change of the transmission path of noise caused by the change of vehicle operating conditions . Related Articles | Metrics

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Simulation and Optimization of a Suspension Mechanism of    Bus’s Air-conditioning Compressors 2015, 35(5): 97-101.  DOI: 10.3969/j.issn.1006-1335.2015.05.020 Abstract ( )   PDF (1637KB) ( )   Based on an improved suspension mechanism of crankshaft air conditioning compressor commonly used in bus and the similarity to automotive powertrain mounting system, a compressor assembly-engine lumped parameter model is built to study the engine and belt vibration. The target, constraints and design values of the optimization are respectively the system energy decoupling grate, system natural frequency as well as suspension stiffness constraints and the three suspension stiffness values. The compressor assembly-engine dynamics model is further established based on ADAMS. The simulation results show that the vibration of improved compressor suspension mechanism is weaker, and the suspension reaction forces, compressor centroid axis of rotation around the vertical displacement and angular acceleration are effectively decreased, which proved the feasibility and effectiveness of the optimized model in compressor vibration isolation. Related Articles | Metrics

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Difference Characteristic Analysis of Cargo Ship Vibration Caused by Low-speed Diesel Engine and Propeller 2015, 35(5): 102-106.  DOI: 10.3969/j.issn.1006-1335.2015.05.021 Abstract ( )   PDF (2004KB) ( )   Related Articles | Metrics

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Application of Modal Radiation Efficiency to the Analysis of    Low-frequency Booming Noise in Mini-cars 2015, 35(5): 107-110.  DOI: 10.3969/j.issn.1006-1335.2015.05.022 Abstract ( )   PDF (1419KB) ( )   Through the application of finite element and boundary element method, set the simplified model of a mini-car`s rear door which simply supported on four sides as the study object. Ascertained the influence law of modal radiation efficiency (20~100Hz) through changing the thickness of the sheet, stiffness and increasing the quality of the "abdominal point" in lower-order modes. Through analysis and rectification work on the interior low-frequency acoustic performance of the car, verify the feasibility of using modal coupling radiation efficiency to guide the rectification of interior low-frequency acoustic problems. Related Articles | Metrics

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Analysis and Control of the Interior Noise and Vibration of a Mini-vehicle 2015, 35(5): 111-115.  DOI: 10.3969/j.issn.1006-1335.2015.05.023 Abstract ( )   PDF (1372KB) ( )   Related Articles | Metrics

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Analysis of Vehicle’s P/T Sensitivity Based on Transfer Path Method 2015, 35(5): 116-120.  DOI: 10.3969/j.issn.1006-1335.2015.05.024 Abstract ( )   PDF (1588KB) ( )   It’s very important to calculate the sound pressure in vehicle from the powertrain torque excitation for advanced vehicle development. In this paper, a detailed full vehicle structure model and a fluid cavity model was built with FE method, and the coupled fluid-structure equations was derived. The model was validated with the method of modal assurance criterion. Based on the models，the sensitivity of sound pressure over toque, which is called P/T, was calculated. In 30-100Hz, the simulation result had a good consistency with the test result, but not in 10-30Hz. The simulation and tests of mount isolation and powertrain rigid body modes were completed and the results were analyzed. The influence of mount dynamic-stiffness characteristics on P/T was proved. Finally, when the mount dynamic stiffness value was increased, the P/T simulation and tests had a good consistency in the whole band of 0-100Hz. Related Articles | Metrics

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Numerical Simulation Analysis and Structure Optimization of Automotive Exhaust System Noise 2015, 35(5): 121-125.  DOI: 10.3969/j.issn.1006-1335.2015.05.025 Abstract ( )   PDF (1542KB) ( )   For the problem of high noise level of an automotive exhaust orifice, acoustic characteristics of exhaust muffler is analyzed by using the 3D finite element method; internal muffler flow field simulation is performed with computational fluid dynamics method (CFD) to find out the reason for the flow regenerated noise. Exhaust muffler structure is optimized based on the results. The vehicle exhaust tailpipe noise test is conducted with the optimized muffler; the tailpipe noise is reduced significantly, and meets the design target. Related Articles | Metrics

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Noise Pollution and Control of a 500 kV Ground Substation 2015, 35(5): 126-129.  DOI: 10.3969/j.issn.1006-1335.2015.05.026 Abstract ( )   PDF (1308KB) ( )   Related Articles | Metrics

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Experimental Study on Periodic Rubbing Faults of  Gas Lubrication Bearings and High Speed Rotors 2015, 35(5): 130-133.  DOI: 10.3969/j.issn.1006-1335.2015.03.027 Abstract ( )   PDF (1800KB) ( )   Related Articles | Metrics

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Intelligent Control of Torsional Vibration of Rolling Mills Based on Improved BP Neural Network 2015, 35(5): 134-138.  DOI: 10.3969/j.issn.1006-1335.2015.05.028 Abstract ( )   PDF (1223KB) ( )   For the torsional vibration control problem of rolling mill’s drive system, the dynamic model of the drive system of the rolling mill is established considering load torque. Considering the characteristics of torsional vibration model is complicated and not easy to measure the parameters. The state observer is proposed based on neural network, and the standard BP network is optimized. The design of intelligent improved BP neural network observer based control system, and the simulation of the mill examples using simulink. The results show that the design of the smart control system of torsional vibration of the rolling mill drive system has good control effect. Related Articles | Metrics

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Asynchronous Motor Fault Diagnosis Based on Wavelet Packet Approximate Entropy and Weighted LMS 2015, 35(5): 139-144.  DOI: 10.3969/j.issn.1006-1335.2015.05.029 Abstract ( )   PDF (1528KB) ( )   Related Articles | Metrics

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Identification Method for Noise Estimation Distortion in Wavelet Denoising 2015, 35(5): 145-149.  DOI: 10.3969/j.issn.1006-1335.2015.05.030 Abstract ( )   PDF (1196KB) ( )   The noise estimate distortion in the wavelet threshold denoising is researched. When the signal containing some high frequency components is denoised by using the wavelet denoising with usual threshold selection methods, the frequency band energy leakage of the wavelet analysis results in the increase of the noise estimate of the wavelet denoising and makes an error appear in the process of the wavelet threshold denoising. In view of the relevance between the d1 detail level and the d2 detail level, the rules of the noise estimate affected by the frequency band energy leakage from the d2 detail level are analyzed. The identification method for noise estimate distortion is proposed by using the maximum correlation coefficient of the d1 detail level and the d2 detail level. Finally, the method restraining the noise estimate distortion is proposed. The results show that the noise estimate distortion can be distinguished by using the above method, and the problem of the serious useful information loss in the wavelet denoising process can be avoided. Related Articles | Metrics

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Diesel Engine Fault Diagnosis Based on AGMF and Improved Grey Correlation Analysis 2015, 35(5): 150-153.  DOI: 10.3969/j.issn.1006-1335.2015.05.031 Abstract ( )   PDF (1101KB) ( )   Related Articles | Metrics

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Application of Lifting Wavelet Packet and BP-AdaBoost Model to Damage Identification of Cables of  Long-span Cable-stayed Bridges 2015, 35(5): 154-158.  DOI: 10.3969/j.issn.1006-1335.2015.05.032 Abstract ( )   PDF (1296KB) ( )   Related Articles | Metrics

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Local Characteristic-scale Decomposition Method Based on Cubic Hermite Interpolation 2015, 35(5): 159-163.  DOI: 10.3969/j.issn.1006-1335.2015.05.033 Abstract ( )   PDF (1796KB) ( )   Related Articles | Metrics

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Study on Performances of Reactive Muffler Based on CFD and Acoustic Finite Element Methods 2015, 35(5): 164-166.  DOI: 10.3969/j.issn.1006-1335.2015.05.034 Abstract ( )   PDF (1253KB) ( )   Related Articles | Metrics

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An Acoustic Model for Single Cup and Double Degree of Freedom Earmuffs Based on Micro Vibration Theory 2015, 35(5): 167-171.  DOI: 10.3969/j.issn.1006-1335.2015.05.035 Abstract ( )   PDF (1465KB) ( )   Related Articles | Metrics

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Lifespan Prediction of Rubber Vibration Isolators Using Thermal-aging Method 2015, 35(5): 172-175.  DOI: 10.3969/j.issn.1006-1335.2015.05.036 Abstract ( )   PDF (978KB) ( )   Related Articles | Metrics

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Nonlinear Dynamic Characteristics Analysis of a Passive-active Hybrid Vibration Isolation System 2015, 35(5): 176-179.  DOI: 10.3969/j.issn.1006-1335.2015.05.037 Abstract ( )   PDF (1165KB) ( )   Related Articles | Metrics

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Acoustic Performance Evaluation of Chiral Layer Coating Based on Multi-scale Asymptotic Homogenization Theory 2015, 35(5): 180-184.  DOI: 10.3969/j.issn.1006-1335.2015.05.038 Abstract ( )   PDF (1463KB) ( )   Related Articles | Metrics

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Study on Transmission Loss of Complex Mufflers with Perforated Baffles 2015, 35(5): 185-188.  DOI: 10.3969/j.issn.1006-1335.2015.05.039 Abstract ( )   PDF (1268KB) ( )   Related Articles | Metrics

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Experimental Study on the Vortex-induced Vibration of Wavy Stay Cabl 2015, 35(5): 189-192.  DOI: 10.3969/j.issn.1006-1335.2015.05.040 Abstract ( )   PDF (1719KB) ( )   Considering the existing challenges of the flexible stay-cable vibration control under the wind load and wing-rain load, we proposed a new modified wavy stay-cable to suppress the vibration and reduce the drag. By using hot-wire anemometer, Laser displacement sensor, pressure scanning valve, smoke wire and other experimental methods, we studied the vortex-induced vibration(VIV) and Lock-in phenomenon of the wavy stay cable at Re=6800-20480 and the regular stay cable was introduced for comparison. The experimental results indicated that at the same mass ratio and damping ratio, the wavy stay cable with and can also be induced to vibrate as same as straight stay cable, the vibration suppression of wavy stay cable still be existed, the wavy stay cable with is better than wavy stay cable with . Compared with straight stay cable, the vibration suppression is up to 10% with shorter “lock-in” region. One of the main reasons is the large variation of modified wavy stay-cable surface will enhance the secondary spanwise vortex. Once the vortex induced vibration, the stay-cable vibration will be interfered by them, and then the vortex shedding is controlled and the lift fluctuation is suppressed. Related Articles | Metrics

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Damage Detection of Large Generator Stator Insulation Using Guided Wave-based Imaging Method 2015, 35(5): 193-197.  DOI: 10.3969/j.issn.1006-1335.2015.05.041 Abstract ( )   PDF (1422KB) ( )   In order to accurately assess the structure condition of stator insulation, the basic theory of guided wave and probability-imaging method are employed in this study for stator insulation damage detection of large generator. The excitation, propagation and acquisition of guided wave for stator insulation damage detection are simulated by numerical simulation. Finite Element models of four typical insulation damage, i.e. void, delamination, longitudinal and transverse crack are established. Hilbert Transform (HT) was used to extract the time of flight (ToF) of damage scattered wave for damage location. Numerical simulation results reveal that, ToF is an effective feature that can represent the damage location; the A0 mode Lamb wave is more sensitive to the insulation damage. the probability-imaging method can used to not only detect but also accurately locate the specific insulation damage location，which can provide effective information for further study of the stator insulation condition assessment based on the guided wave. Related Articles | Metrics

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Measurement and Analysis of the Low-frequency Vibration Amplitude Modulation in Flue-gas Desulfurization Fans 2015, 35(5): 198-201.  DOI: 10.3969/j.issn.1006-1335.2015.05.042 Abstract ( )   PDF (1588KB) ( )   Related Articles | Metrics

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Cabin Noise Analysis of Vehicles Based on Statistical Energy Analysis Theory 2015, 35(5): 202-206.  DOI: 10.3969/j.issn.1006-1335.2015.05.043 Abstract ( )   PDF (1325KB) ( )   Noise, vibration and harshness (NVH) is a comprehensive measure of the quality of automobiles, and it is especially represented by the cabin noise levels. In the present paper, Statistical Energy Analysis (SEA) modeling technique was employed to analyze and predict the interior cabin noise of an agricultural harvester. The validity of the SEA model was then well verified by on-site measurements. The results revealed that, for the agricultural harvester of interest, the vibration of the back wallboard of the cabin is the main source of its interior noise in the low frequency, while for the high frequency domain the interior noise of the cabin is mainly associated with the exterior noise. Consequently, increasing the structural damping of the back wallboard can effectively reduce the internal noise levels at low frequencies. Meanwhile, increasing the thickness of the cabin wallboard can efficiently reduce the cabin noise level at high frequencies. In addition, reducing the leakage areas in the various subsystems is another effective way of reducing the high frequency cabin noise. Related Articles | Metrics

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Analysis and Control of Low Frequency Noise of Air Source Water Heaters 2015, 35(5): 207-211.  DOI: 10.3969/j.issn.1006-1335.2015.05.044 Abstract ( )   PDF (1504KB) ( )   For a certain type of air source water heaters, referring to the research technology of automobile NVH characteristics，this paper analyzed the frequency distribution of abnormal noise in the data by using testing method to identify the main noise frequency. The substructure finite element model, acoustic finite element model and acoustic-structure coupling finite element model for an air source water heater were built to compute modal frequencies. Through the comparative analysis of the three kinds of modal frequency, the mainly cause of low frequency noise is determined. According to the results of analysis, the structure of air source water heater is optimized, and the optimized product was tested. The results show that, compared with the prototype, low frequency noise of the optimized product is under good control. This paper provides an effective method for the analysis and control of low frequency noise of air source water heater. Related Articles | Metrics

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Influence of Damping Variation on the Dynamic Response of Transmission Lines under Ice Shedding Shocks 2015, 35(5): 212-216.  DOI: 10.3969/j.issn.1006-1335.2015.05.045 Abstract ( )   PDF (1238KB) ( )   Related Articles | Metrics