目的对比2种后路短节段固定方式治疗胸腰段骨折的疗效.方法郑州市第一人民医院收治胸腰段MagerlA型骨折37例,依据就诊顺序分为对照组和治疗组,对照组19例,采取短节段经伤椎椎弓根钉技术（伤椎以及伤椎上下各1椎体各植入2枚椎弓根钉）,...目的对比2种后路短节段固定方式治疗胸腰段骨折的疗效.方法郑州市第一人民医院收治胸腰段MagerlA型骨折37例,依据就诊顺序分为对照组和治疗组,对照组19例,采取短节段经伤椎椎弓根钉技术（伤椎以及伤椎上下各1椎体各植入2枚椎弓根钉）,治疗组18例,采取后路微＂八＂式跨伤椎椎弓根钉植入短节段固定技术,对比2种术式术前、术后、随访期（12~14个月）椎体前缘高度百分比（AVH%）、椎体后缘高度百分比（PVH%）、矢状面指数（sagittal index,SI）及矫正率,以及日本骨科协会评估治疗分数（japanese orthopedic association scores,JOA）功能评分及改善率、内固定失效率等,评价2种术式临床疗效.结果治疗组AVH%矫正率高于对照组（P〈0.05）,PVH%、SI、内固定失效率比较差异无统计学意义（P〉0.05）.JOA评分改善率治疗组优于对照组（P〈0.05）,随访期JOA评分改善率组间比较差异无统计学意义（P〉0.05）.对照组手术时间明显长于治疗组,出血量也高于治疗组,差异有统计学意义（P〈0.05）,2组患者术后住院时间比较差异无统计学意义（P〉0.05）.结论后路微＂八＂式跨伤椎椎弓根钉植入短节段固定技术是治疗胸腰段骨折有效方法,具有良好的生物力学特性.展开更多
Satellite communication develops rapidly due to its global coverage and is unrestricted to the ground environment. However, compared with the traditional ground TCP/IP network, a satellite-to-ground link has a more ex...Satellite communication develops rapidly due to its global coverage and is unrestricted to the ground environment. However, compared with the traditional ground TCP/IP network, a satellite-to-ground link has a more extensive round trip time(RTT) and a higher packet loss rate,which takes more time in error recovery and wastes precious channel resources. Forward error correction(FEC) is a coding method that can alleviate bit error and packet loss, but how to achieve high throughput in the dynamic network environment is still a significant challenge. Inspired by the deep learning technique, this paper proposes a signal-to-noise ratio(SNR) based adaptive coding modulation method. This method can maximize channel utilization while ensuring communication quality and is suitable for satellite-to-ground communication scenarios where the channel state changes rapidly. We predict the SNR using the long short-term memory(LSTM) network that considers the past channel status and real-time global weather. Finally, we use the optimal matching rate(OMR) to evaluate the pros and cons of each method quantitatively. Extensive simulation results demonstrate that our proposed LSTM-based method outperforms the state-of-the-art prediction algorithms significantly in mean absolute error(MAE). Moreover, it leads to the least spectrum waste.展开更多
Ignoring the influence of flow velocity and flow temperature on muffling performance,performance tests were conducted without airflow in the development phase of the muffler which accounts to the difficulty of obtaini...Ignoring the influence of flow velocity and flow temperature on muffling performance,performance tests were conducted without airflow in the development phase of the muffler which accounts to the difficulty of obtaining a perfect match between the actual noise reduction effect and the design goal.Based on the two-load test theory,a set of high-temperature and high-speed airflow simulation measurement devices for the muffler has been built.In order to avoid the impact of high-temperature and high-speed airflow on the sensor,a high temperature resistant sensor holder has been designed for the test rig.The sound pressure has been measured in the pipe by using the lead-out measurement.In addition,a variable impedance load is placed at the end of the test tube to realize the switch between two different impedance loads by the wave handle of the variable impedance load.A sound source correction method is proposed to decrease the random fluctuation of the spectral characteristics of the output noise signal,which is caused by the acoustic impedance variation at the connection between the transition pipeline and the combined sound source system.Finally,an acoustic software has been used to calculate the transmission loss of the muffler in the presence of high temperature airflow.In comparing the experimental measurements and the simulation results,the small difference shows that:the bench not only can effectively simulate high-temperature and flow velocity environment of the engine but also accurately test the transmission loss of the muffler.展开更多
文摘目的对比2种后路短节段固定方式治疗胸腰段骨折的疗效.方法郑州市第一人民医院收治胸腰段MagerlA型骨折37例,依据就诊顺序分为对照组和治疗组,对照组19例,采取短节段经伤椎椎弓根钉技术（伤椎以及伤椎上下各1椎体各植入2枚椎弓根钉）,治疗组18例,采取后路微＂八＂式跨伤椎椎弓根钉植入短节段固定技术,对比2种术式术前、术后、随访期（12~14个月）椎体前缘高度百分比（AVH%）、椎体后缘高度百分比（PVH%）、矢状面指数（sagittal index,SI）及矫正率,以及日本骨科协会评估治疗分数（japanese orthopedic association scores,JOA）功能评分及改善率、内固定失效率等,评价2种术式临床疗效.结果治疗组AVH%矫正率高于对照组（P〈0.05）,PVH%、SI、内固定失效率比较差异无统计学意义（P〉0.05）.JOA评分改善率治疗组优于对照组（P〈0.05）,随访期JOA评分改善率组间比较差异无统计学意义（P〉0.05）.对照组手术时间明显长于治疗组,出血量也高于治疗组,差异有统计学意义（P〈0.05）,2组患者术后住院时间比较差异无统计学意义（P〉0.05）.结论后路微＂八＂式跨伤椎椎弓根钉植入短节段固定技术是治疗胸腰段骨折有效方法,具有良好的生物力学特性.
基金supported by the National High Technology Research and Development Program of China (No. 2020YFB1806004)。
文摘Satellite communication develops rapidly due to its global coverage and is unrestricted to the ground environment. However, compared with the traditional ground TCP/IP network, a satellite-to-ground link has a more extensive round trip time(RTT) and a higher packet loss rate,which takes more time in error recovery and wastes precious channel resources. Forward error correction(FEC) is a coding method that can alleviate bit error and packet loss, but how to achieve high throughput in the dynamic network environment is still a significant challenge. Inspired by the deep learning technique, this paper proposes a signal-to-noise ratio(SNR) based adaptive coding modulation method. This method can maximize channel utilization while ensuring communication quality and is suitable for satellite-to-ground communication scenarios where the channel state changes rapidly. We predict the SNR using the long short-term memory(LSTM) network that considers the past channel status and real-time global weather. Finally, we use the optimal matching rate(OMR) to evaluate the pros and cons of each method quantitatively. Extensive simulation results demonstrate that our proposed LSTM-based method outperforms the state-of-the-art prediction algorithms significantly in mean absolute error(MAE). Moreover, it leads to the least spectrum waste.
基金Supported by National Key Research and Development Program(2016YFD0700704B)。
文摘Ignoring the influence of flow velocity and flow temperature on muffling performance,performance tests were conducted without airflow in the development phase of the muffler which accounts to the difficulty of obtaining a perfect match between the actual noise reduction effect and the design goal.Based on the two-load test theory,a set of high-temperature and high-speed airflow simulation measurement devices for the muffler has been built.In order to avoid the impact of high-temperature and high-speed airflow on the sensor,a high temperature resistant sensor holder has been designed for the test rig.The sound pressure has been measured in the pipe by using the lead-out measurement.In addition,a variable impedance load is placed at the end of the test tube to realize the switch between two different impedance loads by the wave handle of the variable impedance load.A sound source correction method is proposed to decrease the random fluctuation of the spectral characteristics of the output noise signal,which is caused by the acoustic impedance variation at the connection between the transition pipeline and the combined sound source system.Finally,an acoustic software has been used to calculate the transmission loss of the muffler in the presence of high temperature airflow.In comparing the experimental measurements and the simulation results,the small difference shows that:the bench not only can effectively simulate high-temperature and flow velocity environment of the engine but also accurately test the transmission loss of the muffler.
