Detection Method for R-Wave of ECG Signal With Wavelet Transform

The R-wave of ECG signal represents the electrical activation of the ventricles, which initiates ventricle contraction, and the typical peak value singular signal, so the R-wave of ECG signal is localized precisely and analyzed accurately using the wavelet transform. The principium of the precise detection method for R-wave in ECG signal is researched. The special properties of Mexican hat wavelet in time-domain are analyzed, too. This wavelet has every order continuity, symmetry, exponential attenuation and one vanishing moment. For this reason, the mexican hat wavelet basis has the excellent localization and analyzing precision. Using the MIT/BIH (Massachusetts Institute of Technology / Boston's Beth Israel Hospital) Arrhythmia Database and the applications in clinic, the precise detection method can detect accurately and localize precisely to the R-wave in ECG signal in the serious noise signal. This method has the quite high locating precision (its error is not more than one sampling point and the points of the R-wave in ECG signal about 80 percent are localized precisely) and analyzing accuracy (no accumulative error). The real-time of the method is excellent, and the real-time detection to the R-wave of ECG signal can achieve using this method.     

EEG Signal Denoising Based on Wavelet Transform

The article focuses on the method of noise cancellation for EEG signal. The method of notch filter is discussed. According to the frequency of noise and the principle of notch filter, the design result of the notch filter and the denoised signal are presented. Then, the analysis of EEG signal are proposed based on wavelet transform (WT) and noise cancellation using WT. Wavelet transform is a multi-resolution time-frequency analysis method. It can decompose mixed signal into signals at different frequency bands. The EEG signal is analyzed and denoised using WT, then the results are presented respectively. Comparing the experiment results shows that WT can detect and process noise in the EEG signal effectively.     

Optimal Control of Semi-Active Suspensions with ER Shock Absorber

An ER shock absorber with mixed mode is designed and its mathematical model is built. The optimal control method with LQ is applied to semi-active suspension systems in vehicle. A optimal output tuner is designed on basis of 1/4 dynamic model and the characteristics of the ER shock absorber. Its aim function and the weighting parameter matrix are determined. The feedback gain vector is found from solving the Algebraic Equation. The result shows that the optimal controller could not only diminish the body acceleration effectively but also improve the ride and handling characteristics. The construction of the ER shock absorber is reasonable and its performance meets the optimal control requirements of semi-active suspension system under the 3 kV/mm. In additional, the optimal control has low cost and energy consumption as well as rapid response . Such a system can meet with the requirements of semi-active suspension control completely.     

The frequency detection model with anti-noise in the autonomous chaotic system

A method of detecting the signal frequency which is disturbed by the noise based on the autonomous chaotic system is proposed. A signal with noise was added to an autonomous chaotic system, and then a negative feedback was imposed to it. The feedback gain was appropriately adjusted, so as to let the noisy system orbit be a limit cycle. The number of times that the orbit went directly through a plane was calculated by loop phase technology, and the vibration frequency was found according to it. The frequency of system is determined by the frequency of the test signal, yet free from noise, so the frequency of the test signal is the vibration frequency of the system. Simulation results further demonstrate the effectiveness of the method.     

Denoise Based On Translation Invariance Wavelet TransformAnd Its Applications

De_noising algorithm based on traditional wavelet transform may produce artifacts on discontinuities of the signal. The reason is that the de_noising algorithm lacks of wavelet translation invariant. This paper proposes a de_noising method based on translation invariant. The method performs the cycle_spinning for the signal to be analyzed. And then, the soft (hard) thresholding is used to shrink the wavelet coefficient of the signal and reconstruct the signal. Consequently, the shift dependence of wavelet basis is eliminated. This method can suppress the artifacts effectively so that de_noised signal is more smooth and has better approximation to original signal.     

A Practical Method of Eliminating the White Noise of Partial Discharge with Wavelet

The white noise of PD(partial discharge) signal brings great difficult to the PD signal's processing, so eliminating the white noise is a necessary section. There are many methods of eliminating white noise, but none of them are suitable to the PD signal processing. Because PD signal and white noise have different Lipschitz exponents and different wavelet transform features in time-scales, a new eliminating white noise method has been brought forward that has simple operation and meets the timing need of PD signal's processing. After the processing with this method, the PD signal is not distortion and the effect of eliminating white noise is very good. This method can be applied to the processing of PD signal gotten from the site.     

Development of General Measurement & Control Software Platform for Automobile Components Test

This paper has discussed the characteristics of the development of automobile components test system.Based on the development example of vehicle hyraulic shock absorber test system,the paper has built general measurement & control software platform for automobile components tests,carved up main function modules along with the class libraries for platform,and adopts multi-thread technology to guarantee platform's real-time performance.The platform has enough flexible and extensible capability,and can satisfy the requirements of software developing for modern automobile components test system.     

Comparative study on the identification of structural modal parameter using different methods

Chongqing Chaotianmen Yangtze River Bridge is the world's longest-span arch bridge. The node connections on its main truss’s lower chords are to bear millions of large-amplitude stress cycles caused by automobile and light-rail train loads. However, there exists no referential designing and testing experience in such detailing on long-span steel bridges at home and abroad as yet. High-cycle fatigue behavior testing on a detailing model has been conducted to study the fatigue reliability of the bridge’s critical node connections. The testing cycling load on the model is determined according to conventional specifications and the expected traffic flow on the Bridge. The 1/2-scale detailing model is carefully fabricated to simulate the node prototype and undergo the 2 million-cycle testing with the design load. Through testing, fatigue reliability of Chaotianmen Yangtze River Bridge’s main-truss lower-chord node connections during the design service life is verified. In addition, static test data are compared with those calculated by finite element analysis to prove the validity of the node model. In the end, fatigue destruction test of the model was carried out to get the fatigue failure law of the node connection and provide necessary parameters and reference for designing and monitoring of this bridge in the future.     

Filtering Construct of Adaptive Filter Grou Pwith Multi-scale Decomposition

The principle and method of the adaptive filter and the filtering with wavelet transform were analyzed, and the model and method of adaptive filtering with wavelet transforms for the transient signal was established. The separated noise of signal by the multi-scale decomposition of wavelet transforms, was the input signal of adaptive filter, and accordingly the optimal filtering method of signal-noise decomposition was realized. By the adaptive filter grou Pbased on the wavelet transform, the optimal filtering to the multi-noise of signal is achieved at the same time, and the method presented in this paper has the excellent filtering capability. Examples of application demonstrate that this method presented is excellent to realize the optimal estimate to the valuable signal and noise of the transient signal in the same frequency segment.     

FAST ADAPTIVE FILTERING ( FAF ) FOR THE PROCESS DETECTION CONTROL SYSTEMS

The limitation of LMS adaptive noise cancelling (ANC ) is analyzed here. Based on the discussing of general signal and noise model of process detection control system, a fast adaptive filtering(FAF) is proposed on the basis of modelling the correlativity between the noise and it's correlative noise with the view of large noise. Fast transversal filtering ( FTF ) adaptive, algorithms is used to imitate the correlative modelling. Both simulation and experiments show that the method presented in this paper is suitable for the process detection control system , and it exhibts better results than the LMS noise cancelling method.     

Test Method of Indoor Noise for Micro-surfacing Mix

Micro-surfacing mix has been wildly used in the pavement maintenance for its water proofing, anti-skidding and wear resistance. However, micro-surfacing pavement has higher noise than the common asphalt pavement and its noise can not be measured effectively and accurately. Therefore, the indoor noise test method of micro-surfacing mix based on wet track abrasion test was explored. The micro-surfacing mix specimens were used to imitate the micro-surfacing pavement. The wet track abrasion tester was used to provide the vehicle loads. The sound level meter was used to measure the noise between tire and pavement. Furthermore, the indoor noise of nine kinds of micro-surfacing mixes with different gradation was examined. The results show that the equivalent sound level in the second time period has good relationship with the surface texture depth by sad patch method. Then the test method and test procedure for the indoor noise of micro-surfacing mix based on wet track abrasion test were given. Finally, two micro-surfacing mixtures with different gradations were made to validate the test method. The results show that the evaluation method can effectively distinguish the difference of micro-surfacing mixes with different gradation and can supplement the mix design method of micro-surfacing mixes.     

Time-frequency Analysis of Heart Sound

The structural defects of the heart are often reflected in the sounds that heart produces. Because of the non-stationary of the PCG signal, it is important to maintain its time-frequency character. We discuss the Short-Time Fourier Transform (STFT) method and the wavelet method. Some normal and abnormal heart sounds were analyzed by these methods. We can see the advantage and disadvantage of them obviously from the examples.     

Adaptive Enhancementt of Heart Sound Based on Simulink

In the course of recording heart sound, it is inevitable that many kinds of noise will be merged in the main signal. These kinds of noise disbennifit the heart sounds, even import awful influence to analysis result. So, before further processings of phonocardiographic records, noise must be suppressed. Because heart-sound is a highly nonstationary signal, this paper presents the application of adaptive filter method to the elimination of noise,and at the same time, employs the datum of heart-sound plot as the reference noise. With simulink, a modeling and simulation tool for dynamical systems, the model of LMS adaptive heart-sound enhancement is established.Tests prove this method makes effective denoising and heart-sound enhancement.     

Influence of Motorcycle Noise on Gear Transmission

The study of motorcycle's acoustic signal shows that gears noise take a great proportion on the whole acoustic of motorcycle.So how to control the noiseof gears is very helpful for reducing the whole motor's acoustic.This paper discusses the engine matching with transmission system in reason,primary transmission and gear geometry design parameter & the mend of tooth body(tooth form & tooth direction) how to influence the acoustic of motorcycle.The study shows that the gear transmission System's matching with engine in reason can notable improve the efficiency of motorcycle.In the meaning time the exactly choosing the primary transmission gear geometry design parameter and the mend of primary transmission gear's tooth body can effectively reduce the acoustic of motorcycle.This paper has engineering practice sense.     

Multiresolution Wavelet Transform for Detection of EEG Abnormal Rhythms

The signal of brain activity is a non-stationary random signal including lots of physiology and disease information, which is of important action for doctors to judge pathological changes in brain. So the analysis and process of the EEG signals are always attended. In this paper, the authors take account of the time-frequency localization of wavelet transform and use multiresolution wavelet transform to detect EEG abnormal rhythms. The signals of different scales after EEG signals are transformed by multiresolution wavelet transform not only reflect the frequency information of the signals, namely the more great scale is the lower of the frequency of the signals,but also reflect the time information of the signals, namely EEG state at that time. The test results indicate that the abnormal rhythms of the EEG signals can be detected effectively if right wavelet basis is selected.     

Application of Wavelet Denoising in Partial Discharge Online Monitoring of Transformer

Because of the strong interferences, such as discrete spectrum interferences (DSI), white noise and pulse-shaped interferences, it is still a difficult work to extract the partial discharge (PD) signal for transformer online monitoring techniques. Through deeply study on the automatic selection of threshold value and mother wavelet, the wavelet-based de-noising method for partial discharge signals is proposed. The analyzing results on simulation signal and field-measured signal indicate that the proposed method is fit for de-noising white noise but for DSI the comparably worse de-noising results is acquired. Hence it is predicted that good de-noising results will be achieved with the wavelet-based de-noising method combined with digital filtering method fitting for de-noising DSI.     

Study on Surface Noise Distribution of Three ring Reducer

The three ring reducer is a kind of gear drive developed in the past decade. Adopting the new conception of "parallel and movable axis" of multiple mechanisms, this kind of gear drive has many characteristics such as large transmission ratio, high efficiency and so on. As the three ring reducer has been invented only for ten years, up to date the design of the gear drive is only made with analogue method, no design theory can be followed, there exist serious vibration and noise in transmission, which limit its wide application in industry. In this paper, the transmission principle of SHQ50 reducer is studied, the surface noise distribution of the reducer, transmission ratio 49.5 , is measured and analyzed by means of sound intensity method. The 3D distribution maps of noise on top of reducer, input side and output side of reducer, and left side and right side of reducer are drawn. With the sound intensity frequency maps of each measuring point, the sources of giving out noise are analyzed. The reducer of low vibration and noise can be designed rightly according to the analysis.     

THE RESEARCH OF MONITORING AND DIAGNOSING BALL BEARING FATIQUE ON LINE

This paper describes the research work of analyzing vibration signal to monitor and diagnose on line the ball bearing fatique. Carrying out a large mumber of life test on ball bearing test machine, it is discovered that in the so called "second effect" vibration signal as the bearing fatique occurs, apart from the two widely used spetrum charactersof "fraverse frequency" and "high frequency shock pulse" , there is another important but rarely known opcctrum characteristic of high frequency peaks existing in the middle-to-high frequency band.The generating mechanism, effect factors and test method of those high frequency peaks are researched tentativ tentatively. Two binds of device for monitoring abnd diagnos sing ball learing fatique on line are developed based ion this new type spectrum characteristic. One consists of a bandpass filter, the other is based on the spetrum characters which corns from the DDS ( Dynamic Data System ) modeling     

Effective Coefficient Threshold for Complex Wavelet Transform

This paper constructs complex wavelet which used for suppressing white noise in PD,and then analyses some disadvantages of several existing wavelet threshold and presents a method of Effective Wavelet Coefficient(EWC) according to the characteristic of modulus maximum of PD signals.Then it is compared with maximin theory threshold selection and Stein unbiased risk estimate theory threshold selection.The findings suggest that the method of EWC is adaptive,and it can suppress noise completely with small distortion of PD signal.     

贮藏温度和包装方式对红富士苹果贮藏效果的影响

以红富士苹果为试材,分别于0℃和冰温条件下,研究了不同包装材料及保鲜剂对红富士苹果采后贮藏保鲜期间品质变化的影响。结果表明,在冰温条件下,"微孔保鲜袋+高效乙烯吸收剂"和"保鲜袋+化学吸收剂"2种贮藏方式效果最好,延缓了果肉硬度及可溶性固形物(TSS)的下降速率,贮藏8个月仍能保持良好的品质。