为应对红外气体泄漏成像过程中因设备转动等因素导致的图像不稳定及泄漏气体检测效果不佳的问题,提出1种结合图像帧子块匹配法和改进快速鲁棒模糊C均值算法(fast and robust fuzzy c-means,FRFCM)的红外图像细节增强方法。该方法利用图...为应对红外气体泄漏成像过程中因设备转动等因素导致的图像不稳定及泄漏气体检测效果不佳的问题,提出1种结合图像帧子块匹配法和改进快速鲁棒模糊C均值算法(fast and robust fuzzy c-means,FRFCM)的红外图像细节增强方法。该方法利用图像帧子块匹配法配准图像帧,同时引入背景建模和差分方法从背景中分离动态气体目标,并在FRFCM基础上增加自适应调整模糊因子以优化图像帧的羽流强化特征效果。研究结果表明:该方法能够有效去除冗余信息,使图像帧匹配误差降低约75%,对比度增强值提高4.7%,羽流分割的平均交并比达到0.68,在保持较高分割准确度的同时显著提升检测速度,适用于油气田、集输站及氢气站等气体安全检测系统。研究结果可为气体泄漏监测技术的优化与应用提供参考。展开更多
The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensi...The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensional electrical structure of the crust and upper mantle lithosphere was derived from magnetotelluric data inversion along a survey line across the central Yunnan sub-block.Results suggest that the middle and upper crust of the central Yunnan sub-block is comprised of several independent high-resistivity bodies.Deep extension of some faults was revealed according to electrical structure and relocated microseismicity.The Chenghai fault extends downward along the eastern boundary of a high-resistivity body.The Yuanmou fault dips to the west and extends to the depth along the boundary between two high-resistivity bodies.The Tanglang-Yimen fault cuts through a high-resistivity body in the middle and upper crust.There is an obvious high-conductivity C1 layer in the lower crust in the eastern part of the central Yunnan sub-block,and its western border displays an obvious structural boundary in the shallow part.The eastern part of the central Yunnan sub-block moves eastward relative to the western part(bounded by the west side of a high-resistivity body R3 in the C1 west).C1 is speculated to be characterized by low rheological strength and viscosity,thus reducing the resistance to eastward movement of the eastern part.Owing to the combined action of C1 and its western boundary,the eastern materials slip eastward faster relative to R3.Due to South China Block resistance,the middle and upper crust in the eastern part is within a compressional tectonic environment,consistent with the negative dilatation rate and the presence of compressive faults in this region.The C1 ground surface has a low strain rate,indicating weak deformation in this region and rigid motion dominance.Our results suggest that under the decoupling effect of the high-conductivity layer in the lower crust,the independent rigid blocks in the middle and upper crust can also exhibit tectonic deformation characteristics of rigid extrusion.展开更多
在使用OSGEarth三维地球引擎进行大规模地理空间数据可视化时,细节层次(Level of Detail,LOD)技术通过动态调整地形和模型的细节层次,在保证视觉质量的同时,显著降低了计算负载和资源消耗。但在分开叠加影像层与地形层在线服务数据时,...在使用OSGEarth三维地球引擎进行大规模地理空间数据可视化时,细节层次(Level of Detail,LOD)技术通过动态调整地形和模型的细节层次,在保证视觉质量的同时,显著降低了计算负载和资源消耗。但在分开叠加影像层与地形层在线服务数据时,由于两类数据服务层级精度不匹配,渲染时将出现白块、断层塌陷等视觉问题,文章提出了一种通过实时重采样自动创建子瓦片的方案,对影像图层与地形图层的精细层级不同的问题进行双线性重采样,有效解决白块和断层塌陷等现象,拥有良好的应用前景。展开更多
针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于...针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于不同纬度区域CU四叉树深度的分布特性和相邻CU的相关性,对当前CU的划分模式进行提前终止决策;利用梯度差异评估当前CU纹理特性,跳过冗余的水平或垂直划分模式。针对纹理模糊CU,通过纬度采样权重加权的二次比较,判断是否跳过垂直划分模式;利用二维哈尔小波变换系数评估当前CU子块间的差异,判断是否跳过三叉树划分模式。实验结果表明,在全帧内模式下,与VVC官方测试平台相比,所提算法能节省43.85%的编码时间,码率仅增加0.85%,视频质量没有明显下降。展开更多
脉冲噪声是影响电力线通信性能的最主要因素。为了提升极化码在电力线信道的性能,文章提出了分段循环冗余校验码辅助串行抵消列表比特翻转(segmented CRC aid SCL-bit flip,SCA-SCL-BF)译码算法,并在加性高斯白噪声(additive white gaus...脉冲噪声是影响电力线通信性能的最主要因素。为了提升极化码在电力线信道的性能,文章提出了分段循环冗余校验码辅助串行抵消列表比特翻转(segmented CRC aid SCL-bit flip,SCA-SCL-BF)译码算法,并在加性高斯白噪声(additive white gaussian noise,AWGN)信道和电力线信道下进行了仿真。在构造关键集合时引入Rate1子块,避免了全集搜索的复杂度;根据关键集合中比特的位置进行分段,每段翻转一比特,可以实现多比特翻转。仿真结果表明,SCA-SCL-BF算法的性能相较于公开文献中性能在信噪比(signal-to-noiseratios,SNR)大于0dB时有显著提升。该算法对于提升电力线传输性能有重要意义。展开更多
Background: Sub arachnoid block (SAB) performed by traditional landmark palpation technique can be inaccurate. This problem is exacerbated by altered patient anatomy due to obesity and age-related changes. A pre-proce...Background: Sub arachnoid block (SAB) performed by traditional landmark palpation technique can be inaccurate. This problem is exacerbated by altered patient anatomy due to obesity and age-related changes. A pre-procedural ultrasound scan of the lumbar spine has been shown to be of benefit in guiding lumbar epidural insertion in obstetric patients. Information on the use of real-time ultrasound (RUS) guided SAB, to date, been limited. This study compared RUS guided SAB to traditional landmark guided technique in patients undergoing spinal anesthesia for different surgical procedures. Methods: This was a prospective, single center, comparative observational study conducted in the department of anesthesiology at our center. 560 patients who underwent spinal anesthesia either by landmark based technique or real-time ultrasound-guided methods. The primary outcome was the first attempt success rate of dural puncture when employing the two methods. Results: Baseline characteristics were similar in the two study groups. The first attempt success rate of dural puncture in landmark guided group was 64.3% compared to 72.6% in the ultrasound guided group. This difference was not statistically significant. The procedure performance time was significantly shorter with landmark palpation compared to use of real-time ultrasound guided method. Conclusion: Use of RUS-guided technique does not significantly improve the first attempt success rate of SAB dural puncture during spinal anesthesia compared to the traditional landmark-guided technique.展开更多
文摘为应对红外气体泄漏成像过程中因设备转动等因素导致的图像不稳定及泄漏气体检测效果不佳的问题,提出1种结合图像帧子块匹配法和改进快速鲁棒模糊C均值算法(fast and robust fuzzy c-means,FRFCM)的红外图像细节增强方法。该方法利用图像帧子块匹配法配准图像帧,同时引入背景建模和差分方法从背景中分离动态气体目标,并在FRFCM基础上增加自适应调整模糊因子以优化图像帧的羽流强化特征效果。研究结果表明:该方法能够有效去除冗余信息,使图像帧匹配误差降低约75%,对比度增强值提高4.7%,羽流分割的平均交并比达到0.68,在保持较高分割准确度的同时显著提升检测速度,适用于油气田、集输站及氢气站等气体安全检测系统。研究结果可为气体泄漏监测技术的优化与应用提供参考。
基金supported by the Basic Research Project of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.2020IEF0505)the Basic Research Project of the Institute of Earthquake Forecasting,China Earthquake Administration(Grant No.2021IEF0104)the National Natural Science Foundation of China(Grant Nos.U1839205&42174093)。
文摘The central Yunnan sub-block is an important channel for southeast migration of materials in the Qinghai-Xizang Plateau,and therefore a key area to study tectonic movement and deformation.In this study,a three-dimensional electrical structure of the crust and upper mantle lithosphere was derived from magnetotelluric data inversion along a survey line across the central Yunnan sub-block.Results suggest that the middle and upper crust of the central Yunnan sub-block is comprised of several independent high-resistivity bodies.Deep extension of some faults was revealed according to electrical structure and relocated microseismicity.The Chenghai fault extends downward along the eastern boundary of a high-resistivity body.The Yuanmou fault dips to the west and extends to the depth along the boundary between two high-resistivity bodies.The Tanglang-Yimen fault cuts through a high-resistivity body in the middle and upper crust.There is an obvious high-conductivity C1 layer in the lower crust in the eastern part of the central Yunnan sub-block,and its western border displays an obvious structural boundary in the shallow part.The eastern part of the central Yunnan sub-block moves eastward relative to the western part(bounded by the west side of a high-resistivity body R3 in the C1 west).C1 is speculated to be characterized by low rheological strength and viscosity,thus reducing the resistance to eastward movement of the eastern part.Owing to the combined action of C1 and its western boundary,the eastern materials slip eastward faster relative to R3.Due to South China Block resistance,the middle and upper crust in the eastern part is within a compressional tectonic environment,consistent with the negative dilatation rate and the presence of compressive faults in this region.The C1 ground surface has a low strain rate,indicating weak deformation in this region and rigid motion dominance.Our results suggest that under the decoupling effect of the high-conductivity layer in the lower crust,the independent rigid blocks in the middle and upper crust can also exhibit tectonic deformation characteristics of rigid extrusion.
文摘在使用OSGEarth三维地球引擎进行大规模地理空间数据可视化时,细节层次(Level of Detail,LOD)技术通过动态调整地形和模型的细节层次,在保证视觉质量的同时,显著降低了计算负载和资源消耗。但在分开叠加影像层与地形层在线服务数据时,由于两类数据服务层级精度不匹配,渲染时将出现白块、断层塌陷等视觉问题,文章提出了一种通过实时重采样自动创建子瓦片的方案,对影像图层与地形图层的精细层级不同的问题进行双线性重采样,有效解决白块和断层塌陷等现象,拥有良好的应用前景。
文摘针对等矩柱状投影(equirectangular projection,ERP)全景视频多功能视频编码(versatile video coding,VVC)帧内编码复杂度过高的问题,提出一种编码单元(coding unit,CU)快速划分算法。根据ERP采样特性,将编码帧分为不同纬度区域。基于不同纬度区域CU四叉树深度的分布特性和相邻CU的相关性,对当前CU的划分模式进行提前终止决策;利用梯度差异评估当前CU纹理特性,跳过冗余的水平或垂直划分模式。针对纹理模糊CU,通过纬度采样权重加权的二次比较,判断是否跳过垂直划分模式;利用二维哈尔小波变换系数评估当前CU子块间的差异,判断是否跳过三叉树划分模式。实验结果表明,在全帧内模式下,与VVC官方测试平台相比,所提算法能节省43.85%的编码时间,码率仅增加0.85%,视频质量没有明显下降。
文摘脉冲噪声是影响电力线通信性能的最主要因素。为了提升极化码在电力线信道的性能,文章提出了分段循环冗余校验码辅助串行抵消列表比特翻转(segmented CRC aid SCL-bit flip,SCA-SCL-BF)译码算法,并在加性高斯白噪声(additive white gaussian noise,AWGN)信道和电力线信道下进行了仿真。在构造关键集合时引入Rate1子块,避免了全集搜索的复杂度;根据关键集合中比特的位置进行分段,每段翻转一比特,可以实现多比特翻转。仿真结果表明,SCA-SCL-BF算法的性能相较于公开文献中性能在信噪比(signal-to-noiseratios,SNR)大于0dB时有显著提升。该算法对于提升电力线传输性能有重要意义。
文摘Background: Sub arachnoid block (SAB) performed by traditional landmark palpation technique can be inaccurate. This problem is exacerbated by altered patient anatomy due to obesity and age-related changes. A pre-procedural ultrasound scan of the lumbar spine has been shown to be of benefit in guiding lumbar epidural insertion in obstetric patients. Information on the use of real-time ultrasound (RUS) guided SAB, to date, been limited. This study compared RUS guided SAB to traditional landmark guided technique in patients undergoing spinal anesthesia for different surgical procedures. Methods: This was a prospective, single center, comparative observational study conducted in the department of anesthesiology at our center. 560 patients who underwent spinal anesthesia either by landmark based technique or real-time ultrasound-guided methods. The primary outcome was the first attempt success rate of dural puncture when employing the two methods. Results: Baseline characteristics were similar in the two study groups. The first attempt success rate of dural puncture in landmark guided group was 64.3% compared to 72.6% in the ultrasound guided group. This difference was not statistically significant. The procedure performance time was significantly shorter with landmark palpation compared to use of real-time ultrasound guided method. Conclusion: Use of RUS-guided technique does not significantly improve the first attempt success rate of SAB dural puncture during spinal anesthesia compared to the traditional landmark-guided technique.
