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18 February 2013, Volume 33 Issue 1 Previous Issue    Next Issue

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Numerical Research on Stochastic Resonance in Monostable Systems Affected by Two-frequency Signal 2013, 33(1): 1-7.  DOI: 10.3969/j.issn.1006-1335.2013.01.001 Abstract ( )   PDF (1426KB) ( )   null References | Related Articles | Metrics

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Research of Active Control of Coupled Vibration between Multiple CNC Milling Machines and Flexible Foundation 2013, 33(1): 7-11.  DOI: 10.3969/j.issn.1006-1335.2013.01.002 Abstract ( )   PDF (1447KB) ( )   In the light of the active control of coupled vibration system between the multiple milling machines and the flexible foundation, the MIMO coupled isolation system test model is constructed. And on this base, the tasks completed by the Lab VIEW graphical programming software, including vibration signal acquisition, active vibration control and the control signal output. The optimal control method is applied to design the active controller of the isolation system. Test results show that this control method is effective. Related Articles | Metrics

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Modeling of Complicated Flexible Coupled Isolation System Based on Parameter Perturbation 2013, 33(1): 12-15.  DOI: 10.3969/j.issn.1006-1335.2013.01.003 Abstract ( )   PDF (932KB) ( )   Focusing on the difference between mathematical model and actual system, the state-space model of flexible coupled isolation system is constructed by combining impedance-mobility modeling method with matrix transmission modeling method. The state-space model takes account of equipment for isolation, multi-active isolation mounts integrated with passive isolation part and flexible base. The mathematical model of flexible coupled isolation system with parameter perturbation is build up. In the model, parameter changes relative to nominal model are introduced by virtual loop gain method. By matrix transformation, the isolation model reflecting the system modal damping changes and modal frequency changes is deduced, which provides a basis for robust controller design next step. Related Articles | Metrics

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Least Mean M-estimate Algorithm for Active Control ofImpulsive Noise 2013, 33(1): 16-21.  DOI: 10.3969/j.issn.1006-1335.2013.01.004 Abstract ( )   PDF (1379KB) ( )   The classical Filter-x least mean square (FxLMS) algorithm has been widely used in active noise control, but its performance would degrade dramatically in the presence of impulsive noise. In this paper, a new adaptive algorithm with nonlinear devices based on the concept of robust statistics has been presented, whose objective function is the M-estimate function instead of the mean square error(MSE). In this paper, four different M-estimate functions such as Huber function and Hampel’s three parts redescending M-estimate function are used as objective function and computer simulations are carried out to verify the efficiency of the presented algorithm for active impulsive noise control. Compared with the adding windows algorithm modified by Japanese scholar Akhtar, the simulation results also show that the performance of the presented algorithm has a better convergence. Related Articles | Metrics

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Design and Simulation of Multi-point Double-layer?Vibration Isolation System with Active and Passive?Integration 2013, 33(1): 22-26.  DOI: 10.3969/j.issn.1006-1335.2013.01.005 Abstract ( )   PDF (1399KB) ( )   It proposes a novel piezoelectric-rubber combination vibration isolator to meet the vibration isolation needs of precision instruments of space vehicle. Piezoelectric stack actuator and the rubber part have been designed. It proposes a double-layer active and passive integration of vibration isolation system by multi-point support, establishes the dynamics model of vibration isolation system, applies a improved Linear Quadratic Regulator (LQR) optimal control to the double-layer vibration isolation system and has the numerical simulation analysis based on Simulink. Its results show that the vibration isolator can effectively isolate from the displacement excitation of the basis, prove the study of the isolation method in theory is effective and feasible, thus laid the foundation for further experimental studies. Related Articles | Metrics

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Experimental Study on Resonant Frequency Characteristics of Gough-Stewart Parallel Mechanism 2013, 33(1): 27-30.  DOI: 10.3969/j.issn.1006-1335.2013.01.006 Abstract ( )   PDF (1077KB) ( )   Impulse excitation experiments of Gough-Stewart manipulator were conducted at typical configurations with different structural parameters, and the frequency varying with structural parameters and configurations were studied. Firstly, the mechanism was assembled according to certain structural parameters, and accelerometers were laid-out on the moving platform at feature points. Then, pulse excitation was executed at typical configurations, and the acceleration response at three degrees of freedom was recorded. The frequency response function curves were obtained and the resonant frequencies were identified using the analysis software. The resonant frequency varying with configurations were analyzed. Finally, the mechanism was reassembled according to the changed structure parameters, and the experiment process was repeated. The resonant frequency varying with the structure parameters were analyzed. The analysis results can be used for robot dynamic optimization and controller design. Related Articles | Metrics

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Several Practical Approaches for Nonlinear Dynamic Modeling of Metal Rubber 2013, 33(1): 31-36.  DOI: 10.3969/j.issn.1006-1335.2013.01.007 Abstract ( )   PDF (1194KB) ( )   Three practical nonlinear model of dyanamic behavior of metal rubber is presented, the two specific forms of the trace model and the memory-based model is mathimatically derived with details, and the method of parameter separated identification is presented. Parameters of the model are identified with the experimental data of metal rubber, and the theoretical hysteresis curves are reconstructed, and the mechanism of the nonlinear damping behavior in the mathematical model of the metal rubber is analysed. The theoretical loops and the experimental one are close to each other with satisfactory performance. With the comparision of the three theoretical models, conclusion can be obtained that with the simple metathmatical form and the satistifactory precision, the mixed damping model should be the first-line choice in practical engineering. This study provides a prctical and effective method in modeling and the parameter identification of the metal rubber isoaltor. Related Articles | Metrics

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Introduction of Global Software for Prediction of Acoustic Signals on Ships 2013, 33(1): 37-39.  DOI: 10.3969/j.issn.1006-1335.2013.01.008 Abstract ( )   PDF (1034KB) ( )   Several renowned software and methods in the world for prediction of acoustic signature from ships are presented in this article: evaluation software of radiated noise—NDES, evaluation software of target strength—ARTES, integrated radiated noise and self-noise modeling software—FNVNOISE. Prediction of the acoustic signature by above methods have been presented on the basis of theoretical calculation as practical as possible and dedicated database helping designers for essential calculations has been developed for excessively complicated issues. The database and calculation algorithm will be constantly improved and updated through addition and verification of new data in order to provide solutions to problems during future design work. Related Articles | Metrics

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Attitude Control of Air Spring Raft Isolation System 2013, 33(1): 40-44.  DOI: 10.3969/j.issn.1006-1335.2013.01.009 Abstract ( )   PDF (1223KB) ( )   The isolation performance of raft can be improved greatly when adopting air spring isolators. But how to keep raft attitude balance is a challenge for soft isolation system. The influence on raft attitude is given in detailed based on the analysis of disturbance sources of this raft system. It is a potential approach that adjusts pressure of air springs to keep raft attitude balance. The analysis results show that seaway motion, load fluctuation and air spring leakage are the main disturbance sources. The control approach of raft attitude is proved valid. Related Articles | Metrics

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Analysis of Sound Transmission Loss of Laminate Composite Plate Using Transfer Matrix Method 2013, 33(1): 45-50.  DOI: 10.3969/j.issn.1006-1335.2013.01.010 Abstract ( )   PDF (1025KB) ( )   In the case of high frequency sound waves incident, sound transmission loss formula of orthotropic composite laminates was introduced on basis of transfer matrix method. Audio calculated model was established by composite laminates plate, transmission loss was analyzed by researching the laminate lay angle, plate thickness and density of structural parameters of the laminated plate. The results showed that, effected by fabric and basic performance, laying method, laying angle and other factors, Mass Law can not reflect correctly the sound insulation feature of laminated composite plate. Comparison and analysis can show that there is no obvious linearity between composite material density and sound transmission loss; the greater thickness of laminated plate, the greater of sound transmission loss, also, the thickness of each layer is different, which also can cause the change of sound transmission loss; the greater of angel of laminated plate, the greater of sound transmission loss. Related Articles | Metrics

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Resonance Amplitude Characteristics of Power Machinery in Dynamic Conditions 2013, 33(1): 51-55.  DOI: 10.3969/j.issn.1006-1335.2013.01.011 Abstract ( )   PDF (1281KB) ( )   Abstract:The resonance amplitude characteristics of power machinery dynamic condition which speed is in a certain range have a direct impact on the problems of the mechanical strength analysis and the test parameters setting. Firstly, a theoretical analysis with the duhamelintegral to the vibration force response of dynamic conditions have been done. Find that the response of dynamic vibration force do not have the analytic solutions. So do the simulation analysis by the method of numerical integration. Then we get the conclusion that the dynamic conditions resonance amplitude decreased with the increase of acceleration,and when the acceleration decreases to some extent., ,the resonance amplitude of dynamic conditions is even relative to the steady conditions. Finally the resonance amplitude characteristics with the torsional vibration amplitude of 4100QB diesel engine and the structure resonance radiated noise of JFZ172L generator have been proved by experiment. Related Articles | Metrics

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Control of Nonlinear Harmonic Frequency of Electromagnetic Actuator in Active Vibration Control 2013, 33(1): 56-58.  DOI: 10.3969/j.issn.1006-1335.2013.01.012 Abstract ( )   PDF (1097KB) ( )   In this paper, the nonlinear phenomena of electromagnetic actuator in vibration active control system was studied through theoretical analysis and experiment. The reasons which the electromagnetic actuator can generate extra energy at the second harmonic frequency are analyzed during controlling the low frequency line spectrum vibration. The method of harmonic generator adaptive compensating the nonlinear phenomena of the actuator is provided. The experimental results show that the control method is effect through integrating with the feedforward FxLMS algorithm in vibration active control system. Related Articles | Metrics

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Improved Wavelet Packet Algorithm Based on Singular Values 2013, 33(1): 59-63.  DOI: 10.3969/j.issn.1006-1335.2013.01.013 Abstract ( )   PDF (1583KB) ( )   Related Articles | Metrics

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Load Identification of Flexible Structures 2013, 33(1): 64-67.  DOI: 10.3969/j.issn.1006-1335.2013.01.014 Abstract ( )   PDF (1322KB) ( )   This paper studies the load identification and active control for a flexible cantilever beam. An identification method and controller are presented based on the variable structure control (VSC) algorithm. Simulation results ideate that the presented identification method is effective in identifying the external load of the beam and the designed controller is available for the vibration control of the beam. Related Articles | Metrics

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Modeling of Six-DOF Coupled Vibration Isolation System and Its Engineering Application 2013, 33(1): 68-71.  DOI: 10.3969/j.issn.1006-1335.2013.01.015 Abstract ( )   PDF (980KB) ( )   Abstract: In Euclidean space, a single object has six mutually coupled DOF, and arrangement of damper could change arbitrary. Under the premise of small amplitude vibration, this paper deduced the vibration system entire stiffness matrix and damping matrix of vibration isolation model. The deduced stiffness and damping matrix consist of Geometric parameters matrix and physical parameters matrix of damper. In addition, according to state space method a corresponding numerical algorithm code has been programmed and is used in a specific engineering case. Related Articles | Metrics

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Effect of Damping Performance of Magneto-rheological Fluid Damper on Riding Comfort of Vehicle 2013, 33(1): 72-76.  DOI: 10.3969/j.issn.1006-1335.2013.01.016 Abstract ( )   PDF (1109KB) ( )   The damping performance of Magneto-rheological fluid damper (MRD) with disc type orifice is analyzed and test in this paper, and the formula is deduced among the damping characteristic, magnetic flux density and velocity of piston. On the premise of no control strategy, the effect of damping performance change for MRD to vehicle body acceleration and suspension travel is analyzed using 2 DOF suspension systems, the reason for damping performance of MRD is hard to control when piston in higher velocity is pointed out, and the effect of MRD damping performance change with piston velocity is got, all these laid a foundation for its implication in the semi–active vibration control of armored vehicle suspension system. Related Articles | Metrics

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Study on Technique of Prediction and Simulation of Aircraft Noise 2013, 33(1): 77-82.  DOI: 10.3969/j.issn.1006-1335.2013.01.017 Abstract ( )   PDF (1211KB) ( )   Related Articles | Metrics

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Active Noise Control Technology of Air Auxiliary System in Fuel Cell Vehicles 2013, 33(1): 83-89.  DOI: 10.3969/j.issn.1006-1335.2013.01.018 Abstract ( )   PDF (1039KB) ( )   The power system of Fuel Cell Vehicle (FCV) is quite different from traditional cars, which leads to great differences in noise sources between FCV and traditional vehicle. Air auxiliary system is one of the main noise sources of FCV. Active Noise Control (ANC) has become a research focus recent years. It has advantages to the traditional passive noise control in middle- and low- frequency noise control. Because of time variation of noise sources and environments, it is necessary to use Adaptive Active Noise Control (AANC) in middle- and low- frequency noise control of air auxiliary system in FCV. The developing progress of ANC technology was summarized. Based on the basic concept of ANC, ANC research in recent years was expatiated. And the research progress of adaptive algorithm was focused on. Finally, the prospect of ANNC application in the field of vibration and noise reduction of air auxiliary system in FCV was forecasted. Related Articles | Metrics

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Numerical Analysis for Impact of Sound Absorption Treatment on Ship Cabin Noise Radiated from Air-conditioning System 2013, 33(1): 90-95.  DOI: 10.3969/j.issn.1006-1335.2013.01.019 Abstract ( )   PDF (2278KB) ( )   The noise radiated from the air-conditioning system is a major source of noise in ship cabin, and the sound-absorption treatment is an efficient way to reduce the cabin noise. In order to examine the effect of sound-absorption on the noise reduction in cabin, the finite element predictive model of noise radiated from the ventilation pipe into the ship cabin is established. Taking the measured sound pressure as the noise source, the effects of sound-absorptions on cabin wall and ventilation pipe on the ship cabin noise reduction are investigated, which may be used to guide and improve the acoustic design of ship cabin. The cabin noise caused by air-conditioning system’s change is predicted, and the acoustic design is conducted for the specific higher noise, a satisfactory solution for reducing the noise level in cabin is obtained. Related Articles | Metrics

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Study on Subjective Evaluation of Vehicle’s Sound Quality 2013, 33(1): 96-101.  DOI: 10.3969/j.issn.1006-1335.2013.01.020 Abstract ( )   PDF (1244KB) ( )   As for M1 class vehicle sound quality, this paper first proposed subjective evaluation test by considering the subjective feelings. First, collected a large number of sound signals of vehicles as for the database of sound quality evaluation, collected a large number of sound signals as for the database of sound quality evaluation, according to different frequency bands of sound signals show different characteristics, sound signals were divided to different frequency band. Then determined the best proportion of male and female while do subjective evaluation test. And then did sound quality subjective evaluation test by specific paired comparison. Finally, analyzed the test results and obtained: M1 class vehicle sound characteristic is most influenced by the frequency band 500-4000Hz, followed by 20-150Hz, the frequency band above 4000Hz has minimal impact. Related Articles | Metrics

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Simulation of Vibration Isolation Performance and Optimization of Engine’s Mounting System 2013, 33(1): 102-107.  DOI: 10.3969/j.issn.1006-1335.2013.01.021 Abstract ( )   PDF (2502KB) ( )   Abstract:In this paper,a study on an inline-four diesel engine mounting system is conducted.Using the dynamics simulation software for internal combustion engine named GT-CRANK,a virtual ptototype model of engine mounting system is set up.Then the vibration isolation performance of the mouting system is simulated under differernt schemes of mount stiffness.The law that how the variation of mount stiffness in differert directions influences the vibration isolation performance of the mounting system is found after analyzing the simulation result.Ultimately,combined with the influence law ,the optimization of the mount stiffness is conducted to improve the mounting system performance of vibration isolation. Related Articles | Metrics

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Time and Frequency Analysis of Vehicle’s Launch Shudder 2013, 33(1): 108-113.  DOI: 10.3969/j.issn.1006-1335.2013.01.022 Abstract ( )   PDF (1718KB) ( )   Vehicle launch shudder is the severe torsional vibration phenomenon of driveline under different gear and throttle opening while launching in different road load. The phenomenon undergoes three stages, including vehicle launching, severe shudder and smoothly riding. The frequency components and amplitudes of the vibration acceleration signal have significant time-varying characteristics. This paper introduces three methods of time-frequency analysis, such as short time Fourier transform, Wigner-Ville distribution and continuous wavelet transform. On this basis, the appropriate time-frequency method is chosen to analyze the acceleration signal of different positions in the car under the conditions of M2 gear and small throttle opening. Then, the vibration time-frequency characteristics of three stages are revealed. Finally, this paper studies the frequency characteristic of the three stages combined with the FFT. Related Articles | Metrics

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Study on the Effect of Circumferential Backward-skewed Blade on Noise Radiation Characteristic of Axial Pump 2013, 33(1): 114-118.  DOI: 10.3969/j.issn.1006-1335.2013.01.023 Abstract ( )   PDF (1324KB) ( )   The effect of circumferential backward-skewed blade to flow noise radiation of Axial Pump is performed by using hybrid simulation method, in which a coupled vibro-acoustic model is used. The characteristic curves of hydrodynamics and noise radiation with circumferential backward-skewed blade are obtained. The computed results indicate that the only change of circumferential skewed blade may be not increasing the pump head and efficiency, but could decrease the outward noise radiation of pump, which can be applied to design low noise pump. Related Articles | Metrics

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Experimental Study of Flow Noise for a Centrifugal Pump 2013, 33(1): 119-122.  DOI: 10.3969/j.issn.1006-1335.2013.01.024 Abstract ( )   PDF (1193KB) ( )   An experimental system for measuring flow noise of a centrifugal pump is set up. The flow noise of the centrifugal pump with varied impeller radius at different rotary speeds is measured. The measured flow noise increases with the rotary speed and decreases with the blade-tongue clearance. The measured sound pressure level of downstream of the pump is higher than that of upstream for the pump tested. The variations of the sound pressure level difference and its reason are also studied. Related Articles | Metrics

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Review of Research Advances of Water-lubricated  Stern Bearing Noise 2013, 33(1): 123-126.  DOI: 10.3969/j.issn.1006-1335.2013.01.025 Abstract ( )   PDF (662KB) ( )   Bearing noise or abnormal vibration sometimes originate in water-lubricated rubber stern bearings in marine propeller shaft applications during operation at low-speed, overloading and other poor lubrication conditions. And it will affect the comfort of ships, and especially destruct the hidden nature and viability of Underwater Vehicles. Therefore study on the stern bearing noise mechanism carries important theoretical and practical engineering application significance. A review from the definition, noise generation mechanism, influencing factors to vibration beep suppression technique is summarized. Point out that the ship stern bearing noise carries a complicated production mechanism and is subject to many factors. The research of each team is still not systematic or in-depth. Take full account of the influence of various factors, combined with the test and advanced design methods to a comprehensive study to accurately reveal bearing noise generation mechanism is necessary. On this basis, developing a detailed design, manufacture, and installation specification is 0f great significance to ensure the ship quiet design. Related Articles | Metrics

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Optimization of Powertrain Mounting System Based on Chaotic Immune Genetic Algorithm 2013, 33(1): 127-131.  DOI: 10.3969/j.issn.1006-1335.2013.01.026 Abstract ( )   PDF (963KB) ( )   Traditional optimization tends to get a local optimal solution, the premature convergence of genetic algorithm limits its optimization results,so chaotic immune genetic algorithm is applied for parameter optimization of automotive powertrain mounting system. In optimization, choosing six-degree-freedom decoupling of an automotive powertrain mounting system as an objective function, stiffness and installation angle of each mounting was served as the design variable, many kind of constrain conditions were taken into account,such as the matching for appropriate modal frequency of the system,the ratio stiffness of mounting,static shear and compression for mounting and so on. The results showed that the designed algorithm can improve the performance of matching between vehicle and powertrain mounting system, and enhance the performance of vibration isolation. Related Articles | Metrics

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Design and Application of Box in Box in Oilfield Industry 2013, 33(1): 132-135.  DOI: 10.3969/j.issn.1006-1335.2013.01.027 Abstract ( )   PDF (1283KB) ( )   Related Articles | Metrics

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Analysis of Vibration Isolation Performance of Floating Slab Track Structure with Damping Steel Springs 2013, 33(1): 136-139.  DOI: 10.3969/j.issn.1006-1335.2013.01.028 Abstract ( )   PDF (1223KB) ( )      Damping steel spring floating slab track structure is an effective track structure for reducing the vibration of track. In order to analyze the vibration isolation performance, we set up an analytical model of the damping steel spring floating slab track structure, and analyze its harmonic response. By simulating the impacts between the wheel and the rail, we analyze its dynamic transfer characteristics in terms of harmonic excitation, and evaluate the influences on the vibration isolation from several aspects including the floating slab length, stiffness and damping of vibration isolators as well as different loading positions. Related Articles | Metrics

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Location Scheme of Noise Monitoring Terminals in  Vicinity of Airport 2013, 33(1): 140-142.  DOI: 10.3969/j.issn.1006-1335.2013.01.029 Abstract ( )   PDF (906KB) ( )   This paper briefly described the aircraft noise monitoring system, and analyzed the the location of noise monitoring terminal, the method of locate the terminal can be divided into two steps, general arrangement and specific location. The method is applied at Shanghai Hongqiao International Airport, and the practices shows that mensurability of aircraft noise, control of background noise, the influence of local sound field and some other factors should be paid Special attention during the design of monitoring terminal site. Related Articles | Metrics

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Study on Train Caused Ground-borne Vibration 2013, 33(1): 143-147.  DOI: 10.3969/j.issn.1006-1335.2013.01.030 Abstract ( )   PDF (747KB) ( )   nowadays, the railway construction developed quickly in world-wide. It brings to people convience in travelling, meanwhile, the passage of train will caused ground-borne vibration, and have bad influence to the surroundig buildings and people who live there. So in this paper, the enfluence of vibration and the assess criteria are introduced frist, then a summury of the state-of-the-art study on ground-borne vibration using various approaches, and proposed some suggestions and research trend on this subject. Related Articles | Metrics

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Establishment and Analysis of Noise Model for Cumulative Flight Events 2013, 33(1): 148-151.  DOI: 10.3969/j.issn.1006-1335.2013.01.031 Abstract ( )   PDF (814KB) ( )   Over the years, all countries with the problem of airport noise have developed the evaluation parameters, but mostly single flight events were selected as research subjects, and to the long-term continuous flight events, the number of flight events, flight time and other factors are also to be considered. This paper presents some of the parametric models based on the events of cumulative flight model: weighting parameter model and maximum sound level estimation model. And Delphi7.0 software is used to draw flight path and calculate the various parameters. Related Articles | Metrics

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Noise Forecast and Optimal Control Design of Out-door Substation Xu Lu-Wen 2013, 33(1): 152-156.  DOI: 10.3969/j.issn.1006-1335.2013.01.032 Abstract ( )   PDF (1349KB) ( )   In order to effectively reduce the effect of substation noise on surroundings and avoid blindness and randomness in the process of controlling it, a software called Substation ambient noise simulation analysis and optimal control system which based on basic theory of noise propagation is developed to realize optimal control analysis on substation noise. By contrast the actual measurement and simulation of the software ,demonstrated the effectiveness of the software and applied it to the actual substation projectnoise control project.On the one hand, in the process of planning and designing a new substation, find a optimal substation layout through calculating and analyzing noise sources (transformers and so on), buildings, sensitive points, trees and other obstacles to reduce the effect of substation noise on surroundings;On the other hand, in the process of noise abatement, put forward an noise barrier design scheme through optimizing the height and location of barrier and optimally analyze several schemes, to meet the standard of environmental protection requirement and reduce project cost. From the actual example analysis shows that the method in the substation noise control project has a good application value. Related Articles | Metrics

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Relationship between Microphone System and Speech Transmission Index in Lecture Theatres 2013, 33(1): 157-161.  DOI: 10.3969/j.issn.1006-1335.2013.01.033 Abstract ( )   PDF (1171KB) ( )   By testing the Rapid Speech Transmission Index(RASTI) of the acoustic amplification system, in both on and off states, in the multimedia amphitheaters of 21 colleges and universities in a certain city, and by analyzing and fitting the RASTI in both states of measuring points ABCD with MATLAB, we conclude that the RASTI is only increased by turning the acoustic amplification system on, if the measuring point is more than 4 meters from the acoustic source. By introducing the increase factor (IF), computation shows that the acoustic amplification system does not necessarily provide better speech intelligibility for all multimedia amphitheaters. Related Articles | Metrics

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Analysis and Control Measure of Traffic Noise Pollution ofJiaxing City 2013, 33(1): 162-167.  DOI: 10.3969/j.issn.1006-1335.2013.01.034 Abstract ( )   PDF (947KB) ( )   This paper investigated the noise pollution in the urban areas of Jiaxing City. Through the measurement of the noise and traffic flow of the main streets, comprehensive evaluation and analysis of noise pollution are discussed with equivalent continuous A sound level (Leq), cumulative percentile sound level, noise pollution level(LNP), noise pollution index(PN), and traffic noise index(TNI). On the status of the current traffic development in Jiaxing City, the paper analyzed the reasons of the noise pollution and influencing factors, and proposed effective countermeasures of noise control. Related Articles | Metrics

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Research of Characteristics and Limits of Low Frequency Noise to High Voltage Power Facilities 2013, 33(1): 168-172.  DOI: 10.3969/j.issn.1006-1335.2013.01.035 Abstract ( )   PDF (850KB) ( )   This paper mainly introduces the noise characteristics of the high voltage power facilities. we can understand the noise level and frequency spectrum characteristics of the substation equipment and high voltage transmission line through the field test.Another test about the typical transmission facilities for noise of human feeling also investigated by using methods of semantic segmentation and ranking and scoring. Based on this,the low frequency noise limit of the high voltage transmission facilities was put forward.It provide basis for making the environmental protection standard of low-frequency noise limit scientific for the future,which had great social and economic significance. Related Articles | Metrics

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Signal Processing Methods in Fault Diagnosis of Machinery  — Analyses in Frequency Doman 2013, 33(1): 173-180.  DOI: 10.3969/j.issn.1006-1335.2013.01.036 Abstract ( )   PDF (1177KB) ( )   The frequency-domain analysis is the most important and applicable signal processing technology in fault diagnosis for machinery. In the literature, a number of frequency-domain-based methods have been applied to detect faults in machinery and each method has its special features. Therefore, selecting appropriate method plays a pivotal role in inspecting defects based on vibration signals. Characteristics of fault-caused vibration signals and frequency-domain-based methods are summarized in this paper using representative examples, so as to establish a rule of selecting appropriate signal methods of extracting vibration features for different mechanical equipments. The results can be used to improve the precision and reliability of many kinds of fault diagnoses for key components in different machinery. Related Articles | Metrics

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Fault Diagnosis of Rotating Machine Based on Denoising Source Separation 2013, 33(1): 181-186.  DOI: 10.3969/j.issn.1006-1335.2013.01.037 Abstract ( )   PDF (1896KB) ( )   The rotating machinery vibration signal is the important information source of the fault characteristics identification and diagnosis. The denoising source separation (DSS) technology which separates the mixed signals by the statistical characteristics is used in the fault diagnosis. First the basic theory of DSS and its tangent function are studied, and then the analogous signals are separated. The results show that the performance index and correlation coefficients of DSS are better than those of blind source separation. Applying the DSS method to the gas turbine fault diagnosis, the unbalance and pseudo resonance phenomenon have been diagnosed through the measured fault signals in the rotor. This research work shows that the DSS method is efficient in analyzing the fault diagnosis and it provides new ideas and methods for condition monitoring and fault diagnosis of rotating machine. Related Articles | Metrics

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Phase Propagation Characteristics for Fault Location of Rolling Mill Transmission System 2013, 33(1): 187-190.  DOI: 10.3969/j.issn.1006-1335.2013.01.038 Abstract ( )   PDF (1135KB) ( )   When rolling mill appeared abnormal vibration, in addition to fault of certain parts, it may be caused by machine of vibration transmission, therefore it is necessary to find the fault location. This paper introduces a fault location method based on phase propagation characteristics, this method first conducts adaptive noise cancelling processed for vibration signal, then uses Hilbert transform to extract phase and smoothing processing, thus it achieves fault location according to the phase propagation characteristics. Finally it verified effectiveness of this method through the case analysis of rolling mill drive system fault diagnosis. Related Articles | Metrics

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Combined Bearing Fault Diagnosis Method Based on  Energy Aggregation 2013, 33(1): 191-196.  DOI: 10.3969/j.issn.1006-1335.2013.01.039 Abstract ( )   PDF (1577KB) ( )   Combined bearing fault types are varied, and fault signals are interferenced with strong noise. Characteristic frequencies of several faults are adjacent. Aiming at disadvantadges of EMD that it is hard to resolute near frequency fault signals and difficult to separate weak fault signals under strong noise background, a bearing combined fault diagnosis scheme based on energy aggregation is proposed. Firstly, energy aggregation in frequency domain of discrete cosine transform(DCT) and energy aggregation in time domain of singular value decomposition(SVD) are used to preprocess combined fault signals, in order to denoise and separate weak fault signals which frequencies are close. Secondly, separeted signals are analyzed by empirical mode decomposition(EMD), false intrinsic mode functions(IMFs) found by energy analysis are deleted and frequency spectra of right IMFs are analyzed. At last, combined faults are diagnosed by IMFs spectra. The simulated signal and the actual bearing fault signal analysis results show that compared with EMD, this method can resolute adjacent frequency fault signals and distill weak signals under strong noise, and detect combined faults correctly. Related Articles | Metrics

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Damage Identification of Beam Using Wavelet Packet Analysis and Neural Network 2013, 33(1): 197-200.  DOI: 10.3969/j.issn.1006-1335.2013.01.040 Abstract ( )   PDF (910KB) ( )   A study on recognition of damage location and extent for cracked flexible cantilever beam was conducted. Firstly, finite element method was utilized to model the dynamic system. Then, the dynamic response signal was decomposed by using wavelet packet, and the damage indexes were calculated based on wavelet packet energy spectrum. These damage indexes were used as improved BPNN’s input characteristic parameters to recognize the damage location and extent by a two-step identification method. Finally, numerical simulation was carried out. The simulation results demonstrate that the damage location and damage extent of the flexible beam can be recognized accurately by using wavelet packet analysis and improved BP neural network. Related Articles | Metrics

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Vibration and Noise Radiation Control of the Volute of  Centrifugal Fan 2013, 33(1): 201-203.  DOI: 10.3969/j.issn.1006-1335.2013.01.041 Abstract ( )   PDF (1167KB) ( )   When fan works, the problems of vibration and noise are very serious. The vibration and noise radiation of fan volute are mainly researched in this paper and the noise radiation is controlled. The first six modes of the fan volute were obtained by using software simulation and experimental methods. According to the mode of vibration, the strenuous vibration parts of the fan volute were obtained. Butyl rubber damping materials were pasted into these positions to control the vibration of the fan volute. The noise radiation of the fan volute was measured and analyzed before and after control using software simulation and experimental methods. The results showed that the vibration and noise radiation of the fan volute obviously decreased after control. Related Articles | Metrics

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Effect of Compressed Length on the Stiffness of Metal Rubber Vibration Absorber 2013, 33(1): 204-207.  DOI: 10.3969/j.issn.1006-1335.2013.01.042 Abstract ( )   PDF (982KB) ( )   Metal rubber material is a typical kind of non-linear material. Without replacing the metal rubber, the rigidity of metal rubber vibration absorber can be changed by changing the size of metal rubber’s compression during metal rubber vibration assembly. The rigidity’s change of metal rubber vibration absorber proportionates the dimensional change of metal rubber’s compression. It is analyzed theoretically in this paper and verified by 2 groups of compression test. Related Articles | Metrics

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Research of Noise Attenuated Technology of an Inverter Reluctance Motor Lan Jiang-Hua 2013, 33(1): 208-211.  DOI: 10.3969/j.issn.1006-1335.2013.01.043 Abstract ( )   PDF (1071KB) ( )   Analysis the excessive noise problems of an inverter reluctance motor,Detailed study the reason of problem frequency with the spectral analysis,the natural frequency of testing,electromagnetic force calculation method.Discussed the various possible noise reduction method and then proposed the effective noise reduction measures to solve the problem. Related Articles | Metrics

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Theoretical Research of Isolation Frame Structure Based on Friction Pendulum Foundation Sliding 2013, 33(1): 212-217.  DOI: 10.3969/j.issn.1006-1335.2013.01.044 Abstract ( )   PDF (1044KB) ( )   To study the isolation situation of the friction pendulum foundation sliding isolation frame structure, the theory of the friction pendulum system was a basis and the multi-storey reinforced concrete frame structure was selected. The finite element software SAP2000 was used to modeling, the definition of operating conditions, model analysis and data extraction. To analyze the damping effect, seismic response of isolated structures was analyzed and compared with that of fixed base structures, such as the natural period, the floor maximum acceleration response, displacement between floors and interlayer shear forces. Analysis results indicate that a reasonable parameters set of the isolation layer, formula and program analysis results agrees well with each other. The FPS technology has obviously damping effect and it can decrease the maximum response of structure sharply when earthquake occurs, including the natural period, acceleration response, the layer displacement and interlayer shear. Some of the damping rate even exceed 90%. Related Articles | Metrics

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Effects of Titanium Potassium Whisker on MaterialsBraking Noise Reduction 2013, 33(1): 218-222.  DOI: 10.3969/j.issn.1006-1335.2013.01.045 Abstract ( )   PDF (944KB) ( )   为了降低刹车材料的噪声问题，在复合摩擦材料中添加钛酸钾晶须提高保证耐磨性的同时，研究钛酸钾晶须作为降噪材料对制动噪声的影响情况。通过改变钛酸钾晶须添加量和制动温度，发现随着钛酸钾晶须的增加，噪音声压值呈降低趋势；噪声波动性主要表现在低温段和高温段。通过SEM形貌进行分析，摩擦形貌的特征与噪声的产生与变化具有一致性；形貌表现缺陷较多的样件，噪声声压值较高。 Related Articles | Metrics