To improve the quality of ultrasonic elastography, by taking the advantage of code excitation and frequency compounding, a transmitting-side multi-frequency with coded excitation for elastography （TFCCE） was propose...To improve the quality of ultrasonic elastography, by taking the advantage of code excitation and frequency compounding, a transmitting-side multi-frequency with coded excitation for elastography （TFCCE） was proposed. TFCCE adopts the chirp signal excitation scheme and strikes a balance in the selection of sub-signal bandwidth, the bandwidth overlap and the number of sub-strain image based on theoretical derivation, so as to further improve the quality of elastic image. Experiments have proved that, compared with the other optimizing methods, the elastographyic signal-to-noise ratio（Re-SN） and contrast-to-noise ratio（Re-CN） are improved significantly with different echo signal-to-noise ratios （ReSN） and attenuation coefficients. When ReSN is 50 dB, compared with short pulse, Rc-SN and Re-CN obtained by TFCCE increase by 53% and 143%, respectively. Moreover, in a deeper investigation （85-95 mm）, the image has lower strain noise and clear details. When the attenuation coefficient is in the range of 0-1 dB/（cm.MHz）, Re-SN and Re-CN obtained by TFCCE can be kept in moderate ranges of 5〈Re-SN〈6.8 and 11.4〈Re-CN〈15.2, respectively. In particular, for higher tissue attenuation, the basic image quality cannot be ensured with short pulse excitation, while mediocre quality strain figure can be obtained by TFCCE. Therefore, the TFCCE technology can effectively improve the elastography quality and can be applied to ultrasonic clinical trials.展开更多
Based on impulse and vibration machining theories,a mathematical model of cutting force for the electroplated diamond ultrasonic wire saw was established using superposition principle.The differences between the cutti...Based on impulse and vibration machining theories,a mathematical model of cutting force for the electroplated diamond ultrasonic wire saw was established using superposition principle.The differences between the cutting forces with and without ultrasonic effect were analyzed theoretically and experimentally.The results indicate that the cutting force of diamond wire increases along with the spindle speed decrease and the lateral pressure increase.The force in ultrasonic vibration cutting is about 20% to 30% less than that in conventional cutting.Also,the cutting trajectory of single diamond grit in sawing process is simulated,and the reason that the ultrasonic vibration can reduce the cutting force is explained further.展开更多
Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoe...Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.展开更多
The influence of different technological parameter on material remove rate and surface quality of ZrO2 ceramics is studied using the cutting machining method of electroplate diamond wire saw with ultrasonic vibration....The influence of different technological parameter on material remove rate and surface quality of ZrO2 ceramics is studied using the cutting machining method of electroplate diamond wire saw with ultrasonic vibration.Experimental results show that,compared with the same experiment condition without ultrasonic vibration,this cutting method has the advantages of high material remove rate,good surface quality,little brokenness and so on.展开更多
近年来随着经济的发展,室内定位系统的需求越来越迫切.传统的室内定位系统如WIFI定位和蓝牙定位面临着定位精度低、易受非视距(non-line-of-sight,NLOS)和噪声干扰等挑战.针对这些问题,提出了一种基于融合集成学习的近超声室内定位方法...近年来随着经济的发展,室内定位系统的需求越来越迫切.传统的室内定位系统如WIFI定位和蓝牙定位面临着定位精度低、易受非视距(non-line-of-sight,NLOS)和噪声干扰等挑战.针对这些问题,提出了一种基于融合集成学习的近超声室内定位方法.首先,使用优化的增强互相关方法有效地抵消多径干扰.与传统基于峰值提取或固定阈值的方法相比,此法在混响环境中明显提升了测距的精度.然后,利用到达时间差(time difference of arrival,TDOA)作为特征进行提取.最终,采用了融合集成学习模型,对设定好的训练集进行交叉融合训练,并输入特征,从而得到修正的定位结果.仿真和实验测试结果表明,所提出的方法可以在室内NLOS和噪声干扰的情况下克服较大误差实现精确定位,并且精度优于对比方法50%~90%.本文核心数据公布在https://github.com/ChirsJia/JSJYF上.展开更多
基金Project(2013GZX0147-3) supported by the Natural Science Foundation of Sichuan Province,China
文摘To improve the quality of ultrasonic elastography, by taking the advantage of code excitation and frequency compounding, a transmitting-side multi-frequency with coded excitation for elastography （TFCCE） was proposed. TFCCE adopts the chirp signal excitation scheme and strikes a balance in the selection of sub-signal bandwidth, the bandwidth overlap and the number of sub-strain image based on theoretical derivation, so as to further improve the quality of elastic image. Experiments have proved that, compared with the other optimizing methods, the elastographyic signal-to-noise ratio（Re-SN） and contrast-to-noise ratio（Re-CN） are improved significantly with different echo signal-to-noise ratios （ReSN） and attenuation coefficients. When ReSN is 50 dB, compared with short pulse, Rc-SN and Re-CN obtained by TFCCE increase by 53% and 143%, respectively. Moreover, in a deeper investigation （85-95 mm）, the image has lower strain noise and clear details. When the attenuation coefficient is in the range of 0-1 dB/（cm.MHz）, Re-SN and Re-CN obtained by TFCCE can be kept in moderate ranges of 5〈Re-SN〈6.8 and 11.4〈Re-CN〈15.2, respectively. In particular, for higher tissue attenuation, the basic image quality cannot be ensured with short pulse excitation, while mediocre quality strain figure can be obtained by TFCCE. Therefore, the TFCCE technology can effectively improve the elastography quality and can be applied to ultrasonic clinical trials.
基金Sponsored by Liaoning Innovation Team Fundation(2008T164)
文摘Based on impulse and vibration machining theories,a mathematical model of cutting force for the electroplated diamond ultrasonic wire saw was established using superposition principle.The differences between the cutting forces with and without ultrasonic effect were analyzed theoretically and experimentally.The results indicate that the cutting force of diamond wire increases along with the spindle speed decrease and the lateral pressure increase.The force in ultrasonic vibration cutting is about 20% to 30% less than that in conventional cutting.Also,the cutting trajectory of single diamond grit in sawing process is simulated,and the reason that the ultrasonic vibration can reduce the cutting force is explained further.
基金Sponsored by Zhejiang Province Scientific and Technological Key Task Program (2007C21025)Ningbo Science and Technological Key Task Program (2007B10010)
文摘Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.
基金Sponsored by Department of Education University Research Project of Liaoning Province(LN566)
文摘The influence of different technological parameter on material remove rate and surface quality of ZrO2 ceramics is studied using the cutting machining method of electroplate diamond wire saw with ultrasonic vibration.Experimental results show that,compared with the same experiment condition without ultrasonic vibration,this cutting method has the advantages of high material remove rate,good surface quality,little brokenness and so on.
文摘近年来随着经济的发展,室内定位系统的需求越来越迫切.传统的室内定位系统如WIFI定位和蓝牙定位面临着定位精度低、易受非视距(non-line-of-sight,NLOS)和噪声干扰等挑战.针对这些问题,提出了一种基于融合集成学习的近超声室内定位方法.首先,使用优化的增强互相关方法有效地抵消多径干扰.与传统基于峰值提取或固定阈值的方法相比,此法在混响环境中明显提升了测距的精度.然后,利用到达时间差(time difference of arrival,TDOA)作为特征进行提取.最终,采用了融合集成学习模型,对设定好的训练集进行交叉融合训练,并输入特征,从而得到修正的定位结果.仿真和实验测试结果表明,所提出的方法可以在室内NLOS和噪声干扰的情况下克服较大误差实现精确定位,并且精度优于对比方法50%~90%.本文核心数据公布在https://github.com/ChirsJia/JSJYF上.
