A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in exist...A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible.展开更多
A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteris...A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.展开更多
【目的】应用定量超声技术(quantitative ultrasound,QUS)评价佝偻病婴儿骨状况,为临床治疗提供参考依据。【方法】采用以色列Sunlight公司的Omnisense7000P型定量超声仪对162例佝偻病患儿与正常婴儿进行胫骨声波速度(speed of sound,S...【目的】应用定量超声技术(quantitative ultrasound,QUS)评价佝偻病婴儿骨状况,为临床治疗提供参考依据。【方法】采用以色列Sunlight公司的Omnisense7000P型定量超声仪对162例佝偻病患儿与正常婴儿进行胫骨声波速度(speed of sound,SOS)测量。采用SPSS 13.5对数据进行统计分析。【结果】佝偻病患儿与正常婴儿的胫骨声波速度在出生季节、户外活动时间、正规服用钙剂和VD等方面差异有高度统计学意义(P<0.01)。佝偻病患儿治疗前后的胫骨声波速度差异有统计学意义(P<0.05)。【结论】可应用定量超声技术监测正常小儿的骨状况及佝偻病患儿的治疗效果。展开更多
文摘A novel self-contained in situ sediment acoustic measurement system based on hydraulic driving penetration is proposed to solve the problem of large disturbances to sediments of the in situ equipments already in existence. By using a hydraulic driving device, the system drives four acoustic probes into sediments at an even speed, and this decreases disturbances to sediments introduced by the penetration of acoustic probes. By means of the special design of the central control unit, the system can work full-automatically and the data are stored self-containedly, and this avoids the requirement of real-time remote controlling from the ship. Its operating water depth, measuring depth and measuring frequency is 500m, 1.0m and 30kHz respectively. A set of in situ sound speeds and attenuation coefficients of sediments are obtained at 40 stations using the system. The results confirm that the data obtained by the in situ sediment acoustic system are accurate and credible.
基金Project(2682013BR009)supported by the Fundamental Research Funds of the Central Universities,ChinaProject(2011AA11A103-2-2)the National High-Technology Research and Development Program of China
文摘A schematic to make the spectra of the exterior noise of high speed railway was put forward. The exterior noise spectrum was defined based on the characteristics of the high-speed train exterior noise. Its characteristics considered here include identifying the exterior main sources and their locations, their frequency components including the Doppler effect due to the noise sources moving at high speed, the sound field intensity around the train in high-speed operation, the sound radiation path out of the train, and the pressure level and frequency components of the noise at the measuring points specified by the International Organization for Standardization(ISO). The characteristics of the high-speed train exterior noise of the high speed railways in operation were introduced. The advanced measuring systems and their principles for clearly indentifying the exterior noise sources were discussed in detail. Based on the concerned noise results measured at sites, a prediction model was developed to calculate the sound level and the characteristics of the exterior noise at any point where it is difficult to measure and to help to make the exterior noise spectrums. This model was also verified with the test results. The verification shows that there is a good agreement between the theoretical and experimental results.
文摘【目的】应用定量超声技术(quantitative ultrasound,QUS)评价佝偻病婴儿骨状况,为临床治疗提供参考依据。【方法】采用以色列Sunlight公司的Omnisense7000P型定量超声仪对162例佝偻病患儿与正常婴儿进行胫骨声波速度(speed of sound,SOS)测量。采用SPSS 13.5对数据进行统计分析。【结果】佝偻病患儿与正常婴儿的胫骨声波速度在出生季节、户外活动时间、正规服用钙剂和VD等方面差异有高度统计学意义(P<0.01)。佝偻病患儿治疗前后的胫骨声波速度差异有统计学意义(P<0.05)。【结论】可应用定量超声技术监测正常小儿的骨状况及佝偻病患儿的治疗效果。
