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.     

比较螺杆式与活塞式压缩机在冷库应用中的节能效果

从理论上分析了活塞式压缩机与螺杆式压缩机的性能特点,以实例论证了螺杆式压缩机比活塞压缩机在冷库系统的实际运行中节能效果明显.     

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.     

Research of Compressor Maintenance Service System Basis on Web

The significance and current-situation of running remote maintenance are introduced. The model of maintenance service system is built on the basis of studying units. The system construction, software and hardware environment are debated. The signal monitoring software system of compressor is implemented by programming with assemble language and C language. The virtual instrument applied to on/off-line signal processing is established on the basis of Labwiew. The maintenance decision supporting system interior enterprise with TCP&UDP and the remote maintenance service system adopting B/S model are dwelled. The system is practicability testified. The goal of system developing is the integrated of all kinds of MIS.     

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.     

Identifying Research on Noise Sources of Rotary Vane Compressor

This paper describes the noise mechanism of rotary vane compressor JSS -96 by the method of running independently, spectrum and the measurement of the sound intensity. The noise sources of this type compressor mainly include noise of electromotor, outlet noise and intake noise. Electromotor noise and outlet noise among them have most influence on the compressor noise. This is the further basis of noise control for rotary vane compressor.     

Hopfield Network Models of Water Quality Evaluation

In this paper, a Hopfield model for complex water quality evaluation is presented using the artificial neural network for water quality evaluation. The model is examined with the practical data of water quality from Fengzui River located at Nanchuan city in Chongqing. The results show that Hopfield network is fit for water quality evaluation.     

Subjective preference evaluation and analysisof motorcycle sound quality

Noise samples of motorcycles at different engine speeds taken at the position of the ear of a motorcycle operator are selected as the evaluation stimuli to investigate sound preferences of motorcycle sound quality. Subjective testing is carried out via the paired comparison method. Precise calculation of the misjudging rate is adopted to ensure test result reliability. Formulae between subjective preference scores and psychoacoustic parameters are obtained through linear correlation and multi dimensional regression analysis. The results indicate that loudness and roughness are two predominant metrics influencing preference evaluation for motorcycle noise, and the nonlinear equation better describes the dependence of subjective preference scores on psychoacoustic parameters than the linear one.     

The Quality Evaluation of Concrete

The accidents and hidden troubles in constructional engineering quality must be restrained and eliminated.Strictly controlling the quality of concrete is a key link of ensuring constructional engineering quality.To strengthen the quality evaluation of concrete is an effective measure to improve the quality of concrete.The author takes a living engineering example as an object of the study,considers the compresssive strength of concrete as a focal point,regards the standard engineering criteria as the code of conduct and adopts the mathematical statistics scientifically to assess the control level of construction quality,so as to improve the management level and to promote good quality of engineering.     

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.     

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.     

Subjective and objective analysis on the sound quality of automotive wiper system

Car interior noise induced by windshield wiper system is tested for four different types of cars under high and low wiping speeds,and sound samples for subjective annoyance study are prepared. Grouped pair-wise comparison is adopted for the subjective evaluation test. The characteristic of subjective values and relation of four psychoacoustic parameters to the subjective annoyance are analyzed in two wiping speeds and various wiping patterns. The results indicate that the annoyance caused by wiper noise at high speed is higher than that at low speed,and downwards wiping noise is more annoying than upwards wiping noise. The work concluded that the subjective annoyance of noise from wiper system could be described by binaural loudness and fluctuation.     

酶制剂对馒头品质的影响

在馒头面粉中添加3种不同量的酶制剂,通过对馒头品质的感官评价和质构评价来探讨酶制剂对馒头品质的影响。结果显示,与对照组相比,添加酶制剂对馒头样品的品质均有一定的影响,并且随着添加量的不同而有不同的变化。不同酶制剂及添加量的大小对馒头品质的影响变化存在差异,当真菌α-淀粉酶、木聚糖酶、脂肪酶添加量分别为25×10-6,30×10-6和30×10-6时,馒头品质感官评价最好;当真菌α-淀粉酶、木聚糖酶、脂肪酶添加量分别为20×10-6,40×10-6和30×10-6时,馒头品质质构评价最好。由此看出,不同酶制剂对馒头的作用不同,所以3种酶制剂对馒头品质有重要影响且存在差异。     

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.     

基于旅游角度的城市生态环境质量评价与分析

从旅游角度,对我国生态环境质量进行评价与分析。首先,从气候、大气、声音、园林绿化、交通、市容、环境维护等方面选择10个生态环境质量评价指标,首次把气候条件作为生态环境质量的一个构成方面;其次,利用主成分分析法构建了生态环境质量的综合评价指标;然后,对我国省会城市的生态环境质量进行了评价;最后,对城市生态环境质量与入境旅游流的关系进行了计量分析。主要结论有：我国省会城市的生态环境质量存在较大差异;同一个城市在不同方面的生态环境质量存在较大的差异;气候、园林绿化、车辆通畅等环境质量与入境旅游流存在显著的相关性。     

甘薯茎尖食用品质及产品质量评价的研究

研究了甘薯茎尖不同生长期的营养特性及食用品质,采摘数量和时间对田间产量的影响,产品的营养成分以及系列产品的开发。结果表明,徐薯18号是较好的食用品种,每年的7月底至8月中旬是徐薯18号茎尖最好的食用期和采摘期,其系列产品的香辣味稍优于其他品种。