An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concr...An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.展开更多
In this paper, propagation of sound in pipes under the influence of a gas flow of high temperature is investigated . The analysis in the paper is based on the fundamental equations of fluid mechanics . Approximate for...In this paper, propagation of sound in pipes under the influence of a gas flow of high temperature is investigated . The analysis in the paper is based on the fundamental equations of fluid mechanics . Approximate formulas of the variation of parameters, such as the static tempera -ture, the local velocity of sound , the flow speed and the Mach number, with distance are obtained . The four parameters transmision matix which determines the acoustical character of the pipe is derived and discussed . The acoustical character of a pulsating gas heater is investigated experimentally and theoretically . The theoretical values of the resonant frequencies of the device are in good agreement with the experimental results.展开更多
A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus...A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.展开更多
文摘An example of using ultrasonic method to detect the compactness of complicated concrete-filled steel tube in certain high-rise building was discussed in this study.Because of the particularity of the complicated concrete-filled steel tubular column,the plane detection method and embedded sounding pipe method were adopted in the process of effectively detecting the column.According to the results of the plane detection method and embedded sounding pipe method,the cementing status of steel tube and concrete can be concluded,which cannot be judged by the hammering method in the rectangular steel tube-reinforced concrete.
文摘In this paper, propagation of sound in pipes under the influence of a gas flow of high temperature is investigated . The analysis in the paper is based on the fundamental equations of fluid mechanics . Approximate formulas of the variation of parameters, such as the static tempera -ture, the local velocity of sound , the flow speed and the Mach number, with distance are obtained . The four parameters transmision matix which determines the acoustical character of the pipe is derived and discussed . The acoustical character of a pulsating gas heater is investigated experimentally and theoretically . The theoretical values of the resonant frequencies of the device are in good agreement with the experimental results.
文摘A mixed method for measuring low-frequency acoustic properties of macro-molecular materials is presented. The dynamic mechanical parameters of materials are first measured by using Dynamic Mechanical Thermal Apparatus(DMTA) at low frequen-cies,usually less than 100 Hz; then based on the Principles of Time-Temperature Super-position (TTS),these parameters are extended to the frequency range that acousticians are concerned about,usually from hundreds to thousands of hertz; finally the extended dynamic mechanical parameters are transformed into acoustic parameters with the help of acoustic measurement and inverse analysis. To test the feasibility and accuracy,we measure a kind of rubber sample in DMTA and acquire the basic acoustic parameters of the sample by using this method. While applying the basic parameters to calculating characteristics of the sample in acoustic pipe,a reasonable agreement of sound absorp-tion coefficients is obtained between the calculations and measurements in the acoustic pipe.
