Most economists approach the economy of China from a single visual angle considering it as a special economic modality of transition economy. Based on the analysis from the single visual angle, the paper puts forward ...Most economists approach the economy of China from a single visual angle considering it as a special economic modality of transition economy. Based on the analysis from the single visual angle, the paper puts forward a dual visual angle treating China＇s economy as one of both transition and transformation features, and attempts to research it from this dual visual angle.展开更多
The new type of torsional angle transformer-quarter-wave length hyperbolic secant taper was derived in which the maximum point of surface shear stress is inexistent. The half-wave length complex horns can be composed ...The new type of torsional angle transformer-quarter-wave length hyperbolic secant taper was derived in which the maximum point of surface shear stress is inexistent. The half-wave length complex horns can be composed on the basis of the new taper and quarter-wave taper which may be cylindrical exponential, sirnilar-catenary or similar-cosinc. The resonant frequency and angle amplification ratio of some complex transformers were measured. The experimental results basically agree with the theoretical values. The complex horns have a serics of good characteristics, such as the amplification ratio is very large, the changc of input impedance with the deviation of the frequency is little, the maximum output ultrasonic power is much higher than that of other types of the same material. Therefore, they are very useful horns in high-intensity ultrasonic field.展开更多
A new ultrasound signal processing model that provides fast real-time performance was devel- oped. The model is based on the “rotation angle series fast wavelet transform” algorithm developed for real- time digita...A new ultrasound signal processing model that provides fast real-time performance was devel- oped. The model is based on the “rotation angle series fast wavelet transform” algorithm developed for real- time digital signal processing. Instead of the traditional convolution-based algorithms, the algorithm uses a cascaded structure which can be quickly implemented on digital signal processors. The algorithm runs twice as fast as and is more flexible than the fast wavelet transform, and is applicable for multi-channel and phased array ultrasound systems. By using this algorithm, multi-channel ultrasound systems, including phased array ultrasound systems can have less complex software and hardware designs, lower cost, smaller size, and especially more powerful functions.展开更多
文摘Most economists approach the economy of China from a single visual angle considering it as a special economic modality of transition economy. Based on the analysis from the single visual angle, the paper puts forward a dual visual angle treating China＇s economy as one of both transition and transformation features, and attempts to research it from this dual visual angle.
文摘The new type of torsional angle transformer-quarter-wave length hyperbolic secant taper was derived in which the maximum point of surface shear stress is inexistent. The half-wave length complex horns can be composed on the basis of the new taper and quarter-wave taper which may be cylindrical exponential, sirnilar-catenary or similar-cosinc. The resonant frequency and angle amplification ratio of some complex transformers were measured. The experimental results basically agree with the theoretical values. The complex horns have a serics of good characteristics, such as the amplification ratio is very large, the changc of input impedance with the deviation of the frequency is little, the maximum output ultrasonic power is much higher than that of other types of the same material. Therefore, they are very useful horns in high-intensity ultrasonic field.
基金Supported by the "985" Fund of Tsinghua University (No. 101051)
文摘A new ultrasound signal processing model that provides fast real-time performance was devel- oped. The model is based on the “rotation angle series fast wavelet transform” algorithm developed for real- time digital signal processing. Instead of the traditional convolution-based algorithms, the algorithm uses a cascaded structure which can be quickly implemented on digital signal processors. The algorithm runs twice as fast as and is more flexible than the fast wavelet transform, and is applicable for multi-channel and phased array ultrasound systems. By using this algorithm, multi-channel ultrasound systems, including phased array ultrasound systems can have less complex software and hardware designs, lower cost, smaller size, and especially more powerful functions.
