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.     

Application of Electret Microphone in the Heart Sound Acquisition

Heart sound is a faint signal which is difficult to be acquired. This paper presents the methods for the heart sound acquisition used electret microphone,including the heart sound extraction project, principle, rules and the impedance conversion of microphone. In order to acquire the useful heart sound, the microphone is shielded by a special device. The clinical experiments have indicated that the first and second heart sound can be almost acquired by the microphone, but it is difficult for the third and fourth , which are affected by sex and bodily form.     

Application of Time-frequency Representations in Study on Heart Sound

Heart sound is non-stationary signal, some of its important characteristics can be obtained by time - frequency analysis method. The criteria of different time-frequency representation concentricity of spectrogram, coverage, MSE and regularity of time envelope axe proposed, the performances of Short-time Fourier transform, Wigner - Ville distribution, continuous wavelet transform, and S transform in study on heart sound are compared based on these criteria , and concrete example of application is given.     

Application of Sound Intensity Technique to Measure the Noise of Electromotor

This paper has explained the characteristics,virtue of sound intensity measurement and the principle. And compare with traditional sound pressure measurement. The principle and composing of virtual sound intensity measurement system based on two-channel FFT analysis are researched. The sound power of large turbogeneratorin operating site is determined by means of sound intensity measurement and sound pressuremeasurement. Itis demonstrated that the method of sound intensity measurement of engine is practicable and the measuring data are valid and the method conquers the problems of traditional method of sound pressure measurement which is apt to environmentinfluence and sound power measurement need to especially acoustic environment. It is proved that the sound intensity method is especially suited to determine highaccuratelythe sound Power level of the electrical machines operating in situated conditions especially in case of acoustically worst environments or on loadand themethod is so superiorityin noise measurement.     

Discussion on Limited Noise Value with Specific A-weighted Sound Level for Axial Flow Ventilators

The limited Value of specific A-weighted sound level in the present standard JB/TQh341-84 promulgated by the Ministry,which is applied to determine the unaccuracy of noise characteristics for axial-flow ven tilators has been discussed,Simultaneously a measure that should badopted to reduce the noise of high-pressure&great-flow axial flow ven tilators and a limited standard value for A-weighted Sound level have been also presented,This can not only keep the noise of ventilators up to A-weighted sound level.but also can decrcase the noise of ventilators properly. Purthermore this can make the noise standard for axlal flow ventilators be more scientific and more practica ble.     

Application of Sound Intensity Measurement Method in Spotting the Noise Source of Engine Surface

During the study of noise emitted by accelerating mini-vehicle control, using theory of sound intensity measurement, it is actualized spotting the noise sources with the mini-vehicle engine. In the procees of the contour of sound intensity and frequency spectrum analysis, main noises of the engine are from oil sump tank and delivery menifold shield and two-way branch exhaust pipe shield. These noises are produced from the engine combustion. According to all analysis, the authors bring forward methods of modifying structure of shield-shell parts and consider them as main methods of reducing noises.     

Intelligent Sound Broadcast System of Bus Based on CPLD

The traditional sound broadcast system of bus makes use of MPU. It's shortcoming is have lower dependability, at the same time the maintenance and upgrade is difficult. In order to solve these problems, an intelligent sound broadcast system of bus makes use of Complex Programmable Logic Device(CPLD) and sound chip ISD2560 is introduced, and the principle of design is analysed. Because of the ability of In System Programmability of CPLD's JTAG, and take full advantage of the resource in CPLD, this system have no use for MPU. So, the hard circuit of this system is simple, and the system is easy to debug, upgrade and has very high dependability and better practicability.     

Analysis of the Power System''s Voltage Stabilization by Modeling and Simulink

The simulink of the power system can help people to analyze the actual power system's various state.As an important instrument,the Matlab software gains the recognition because of its all-sided and professional features.But when it is used in the field of dynamic process of the power system,there exist some disadvantages such as the difficulty of the modeling.The state-space module can be used to set up the three rank compact model of the generator and the electrical machine.It makes the modeling more convenient and more easily jointed to the system's primary parameter such as voltage and frequency.The typical model of the power system is built including the generator,electrical wire,load and SVC by using the function of the Simulink.In order to make the model's physical conception,some necessary predigestion is made to the typical model.At last,some conclusions about the voltage stabilization are gained by using the simulink of the system's malfunction,testifing the correctness and feasibility of this compact modeling.     

Corner Point Detection Based on Adaptive Line Approximation

The detection of corner points is one of the basic problems of computer vision. Usually the key question of detecting corner points is how to calculate curvature. This paper presents a novel approach of calculating the backward and forward direction of reference point based on the adaptive line approximation. Our line approximation method objects minimize the distance error and the length of approximation widow adaptively changes with the approximation error. Our adaptive method finds a compromise between the length of approximation widow and the calculation precise. The experiments results show, the method can robustly, effectively and precisely locate corner point for curves with apparent corners with little computation.     

Filtering Method for the Decomposition of Heart Rate Variability Power Spectral

Heart rate variability is a convenient tool to study the autonomic nervous system of human body. It is a focus of studying cardiovascular disease in clinic. The main spectral components are distinguished in the heart rate variability spectrum: ultra low frequency(ULF),very low frequency(VLF), low frequency(LF), high frequency(HF) components .While different part has different physiological meaning. This paper discusses the design of an effective digital filter for heart rate variability power spectral analysis,which provides a scientific measure of heart rate variability power spectral analysis in further studies and clinical applications.     

Adaptive Image Segmentation Method Based on Ncut

In order to solve the problem that requires some factors by manual in the traditional Ncut algorithm, limit the generality of the algorithm, an adaptive image segmentation method is proposed by improving the traditional Ncut algorithm. First, instead of the two control parameters on the calculation of weight matrix that influence the segmentation results in the traditional Ncut algorithm by groups of potential theory; then in order to reduce the sensitive to the number of the cluster and the center of the cluster in the K-means algorithm, calculate on the eigenvector of the Ncut algorithm by the minimum spanning tree, to get the final number of cluster and the center, and then uses the K-means clustering algorithm to get the final segmentation result. The experimental results show that the proposed method not only improves the versatility of the algorithm, and the segmentation is good.     

Analyse of Compressor Sound Quality

By of Stevens steady wide frequency noise loudness and Fastl total sensation noise calculation method, sound quality evaluation of the noise left and back-end face was studied before the compressor improved and after the minipore muffler installed. The research indicates that the compressor noise is reduced, at the same time, the loudness left the compressor and the back - end face is reduced by 10.25 sone and 13.3 sone respectively. The rate reduced is over 40%. The total sensation noise is reduced by 12.5 noy and 15 noy, the rate achieved is over 45%. It is very perfect to improve the compressor sound quality with the use of minipore muffler.     

A Real-time Expert System Based on Adaptive Predication of Process State

The combination of the measured real time state acquisition from the process with predictive process for the fature state is used to predicate the variable tendency for process state. This method is useful to avoid delay and enhance real time ability of the control information of the expert system. Also a described knowledge and structure of real time process state are proposed. This system can be applied to other kind of practice systems with slow time variable, uncertainty and delay.     

Biological Effect of Sound Field Stimulation on Baddy Rice Seeds

The authors adopt the apparatus for sound enhancing plant growth manufactured by themselves. The sound effect of Paddy Rice seeds is researched on the germination rate, germination index, height of stem, increase rate of fresh weight, rooting ability, activity of root system and the penetrability of cell membrane. The study not only validates that sound field stimulation can certainly promote the growth of plant, but also indicates the practicability of the apparatus.     

Brief Study on Physiological Effects of Sound Field on Actinidia Chinensis Callus

Insight into the relationship between plant cell (tissue) and physical stimulation is a focus of biomechanics. In this study, several important plant physiological indexes of Actinidia chinensis callus in sound field including the content of soluble proteins, the activity of SOD, the activity of IAA oxidase and the penetrability of cell membrane, were measured. Some information is got about stress effect through the study and try to explore its mechanism. From the result of experiment,we found that there were a great similarity of stress effect on sound field between Actinidia chinensis and Gerbera Jamesonii acrocarpous , a kind of herbage plant, which had been studied in our lab before. That is to say, the sound field also has dual effect on woody plant. It can enhance or inhibit the growth and development of Actinidia chinensis callus along with the sound field frequency ,and the moderate frequency of sound field acting on the callus could promote callus growth. A conclusion is drawn that the optimal stimulation of sound field are 100 dB and 1 000 Hz. Under the conditions, the sound field can distinctly enhance the growth of Actinidia chinensis callus Whereas, it is not very easy to explore the detail mechanism of environmental stress effects on plant. This paper discussed the mechanism of sound field stress on plant from the level of cell and molecule.     

Improved Sage-Husa algorithm and its application in industrial online measurement

An improved Sage-Husa adaptive filter algorithm is proposed based on the existing methodologies in light of the complex and changing environment of the industrial online measurement. This algorithm,after a new observed value is obtained,first judges whether the filter is in a normal state by the filtering divergence criterion,if not,it judges whether the new observed value is an outlier and takes countermeasures varying with the judgment so as to improve the performance of the Sage-Husa algorithm in industrial measurement. The result indicates that compared with traditional methodologies,this new algorithm is applicable to measure the location of the center point of laser beam in a simulated industrial environment,makes accurate judgment about the system status,features better precision,practicality and robustness and thus can satisfy the requirements of industrial online measurement.