混凝土内部损伤破坏形态具有明显的离散性和随机性,内部损伤特征检测是混凝土细观研究的重要内容.针对已有混凝土结构内部损伤特征检测模型精度低的问题,提出一种特征共享双头Cascade R-CNN模型对混凝土CT图像的损伤特征进行检测.首先,...混凝土内部损伤破坏形态具有明显的离散性和随机性,内部损伤特征检测是混凝土细观研究的重要内容.针对已有混凝土结构内部损伤特征检测模型精度低的问题,提出一种特征共享双头Cascade R-CNN模型对混凝土CT图像的损伤特征进行检测.首先,为了有效识别损伤特征的空间信息,构建具有空间敏感性的fc-head(fully connected head)与空间相关性的conv-head(convolution head)相结合的Cascade R-CNN网络模型;其次,通过特征共享的方法将检测网络各层级分类信息进行融合,提升低IOU(intersection over union)阈值(0.5~0.7) ROI (regions of interest)检测任务的精度.实验结果表明,所提方法在检测混凝土CT图像的损伤特征中平均精度达到91.31%,比原始的Cascade R-CNN提高3.04%,低IOU阈值(0.5~0.7) ROI平均精度提高1.49%,该模型可以较好地从混凝土CT图像中检测出细观损伤部分,具有精度高、运算简单、易于工程实现等特点.展开更多
Purpose:This study was designed to compare the clinical efficacy of"8"and"0"wire fixation systems combined with double-head cannulated compression screws or Kirschner wires for the treatment of tra...Purpose:This study was designed to compare the clinical efficacy of"8"and"0"wire fixation systems combined with double-head cannulated compression screws or Kirschner wires for the treatment of transverse patellar fractures.Methods:From September 2011 to September 2018,patients with closed transverse patellar fractures treated with a double-head compression screw or Kirschner wire were included and analyzed retrospectively.Patients with patellar fractures combined with distal femoral fractures,tibial plateau fracture or preoperative lower limb dysfunction were excluded.The patients treated with the"8"tension band wire fixation system and Kirschner wire were taken as Group A;those treated with the"0"fixation system and Kirschner wire were taken as Group B;those treated with the"8"fixation system and double-head cannulated compression screw were taken as group C;and those treated with the"0"fixation system and double-head cannulated compression screw were taken as group D.Six weeks and one year after the operation and every month from the third month after the operation until the fractures healed,an X-ray examination was performed to identify fracture healing.The time of fracture healing and postoperative complications of the four groups were compared.One year after the operation,knee function was evaluated by Bostman’s score.Results:During the study period,168 patients with patellar fractures were treated by operations,and 88 patients were excluded because the fracture type did not meet the requirements or because there were combined fractures of the distal femur or tibial plateau.As a result,80 patients were included in this study,20 in each group.All the patients were followed up for an average period of 12.2 months.Compared with Group A,patients in Group D presented less postoperative discomfort in the prepatellar region,quicker fracture healing,less fixation failure and better postoperative knee function scores(all p<0.05).The incidence of internal fixation failure in Group(B+D)was lower than that in Group(A展开更多
针对无线传感器网络分簇结构中簇头节点能量消耗过快而容易死亡的问题,提出了一种适合于水稻田监测的混合天线组网通信的能量异构双簇头分簇路由算法。首先估算全网平均剩余能量确定阈值,根据阈值选择主簇头;然后依据节点向主簇头节点...针对无线传感器网络分簇结构中簇头节点能量消耗过快而容易死亡的问题,提出了一种适合于水稻田监测的混合天线组网通信的能量异构双簇头分簇路由算法。首先估算全网平均剩余能量确定阈值,根据阈值选择主簇头;然后依据节点向主簇头节点发送应答信号强弱的原则,确定簇成员节点;最后,按照簇内成员节点剩余能量大小,选择一个副簇头。副簇头负责收集并融合簇内其他成员节点的数据,从而减轻主簇头的能量消耗,降低主簇头的死亡概率。采用能量异构网络对本算法进行仿真,网络节点初始总能量的平均值与同构网络节点初始能量相等,结果显示,该算法异构网络相对于LEACH(low-energy adaptive clustering hierarchy)算法同构网络的稳定周期延长了12.1%。采用无线通信模块nRF905射频芯片和TDJ-0825BKM1定向天线,在水稻田进行混合天线通信试验,测试了定向天线水平覆盖范围;在此基础上的网络模拟试验结果表明,基于该算法的通信网络稳定周期比值相比于LEACH、LEACH-E(LEACH-energy adaptive and uneven cluster)、DEEC(design of energy efficient clustering)、EADC(energy aware data-gathering cluster-heads)4种算法分别提高了46%、47%、58%、11%。该研究可为大面积水稻田无线传感器网络组网进行环境参数实时监测提供理论参考。展开更多
文摘混凝土内部损伤破坏形态具有明显的离散性和随机性,内部损伤特征检测是混凝土细观研究的重要内容.针对已有混凝土结构内部损伤特征检测模型精度低的问题,提出一种特征共享双头Cascade R-CNN模型对混凝土CT图像的损伤特征进行检测.首先,为了有效识别损伤特征的空间信息,构建具有空间敏感性的fc-head(fully connected head)与空间相关性的conv-head(convolution head)相结合的Cascade R-CNN网络模型;其次,通过特征共享的方法将检测网络各层级分类信息进行融合,提升低IOU(intersection over union)阈值(0.5~0.7) ROI (regions of interest)检测任务的精度.实验结果表明,所提方法在检测混凝土CT图像的损伤特征中平均精度达到91.31%,比原始的Cascade R-CNN提高3.04%,低IOU阈值(0.5~0.7) ROI平均精度提高1.49%,该模型可以较好地从混凝土CT图像中检测出细观损伤部分,具有精度高、运算简单、易于工程实现等特点.
文摘Purpose:This study was designed to compare the clinical efficacy of"8"and"0"wire fixation systems combined with double-head cannulated compression screws or Kirschner wires for the treatment of transverse patellar fractures.Methods:From September 2011 to September 2018,patients with closed transverse patellar fractures treated with a double-head compression screw or Kirschner wire were included and analyzed retrospectively.Patients with patellar fractures combined with distal femoral fractures,tibial plateau fracture or preoperative lower limb dysfunction were excluded.The patients treated with the"8"tension band wire fixation system and Kirschner wire were taken as Group A;those treated with the"0"fixation system and Kirschner wire were taken as Group B;those treated with the"8"fixation system and double-head cannulated compression screw were taken as group C;and those treated with the"0"fixation system and double-head cannulated compression screw were taken as group D.Six weeks and one year after the operation and every month from the third month after the operation until the fractures healed,an X-ray examination was performed to identify fracture healing.The time of fracture healing and postoperative complications of the four groups were compared.One year after the operation,knee function was evaluated by Bostman’s score.Results:During the study period,168 patients with patellar fractures were treated by operations,and 88 patients were excluded because the fracture type did not meet the requirements or because there were combined fractures of the distal femur or tibial plateau.As a result,80 patients were included in this study,20 in each group.All the patients were followed up for an average period of 12.2 months.Compared with Group A,patients in Group D presented less postoperative discomfort in the prepatellar region,quicker fracture healing,less fixation failure and better postoperative knee function scores(all p<0.05).The incidence of internal fixation failure in Group(B+D)was lower than that in Group(A
文摘针对无线传感器网络分簇结构中簇头节点能量消耗过快而容易死亡的问题,提出了一种适合于水稻田监测的混合天线组网通信的能量异构双簇头分簇路由算法。首先估算全网平均剩余能量确定阈值,根据阈值选择主簇头;然后依据节点向主簇头节点发送应答信号强弱的原则,确定簇成员节点;最后,按照簇内成员节点剩余能量大小,选择一个副簇头。副簇头负责收集并融合簇内其他成员节点的数据,从而减轻主簇头的能量消耗,降低主簇头的死亡概率。采用能量异构网络对本算法进行仿真,网络节点初始总能量的平均值与同构网络节点初始能量相等,结果显示,该算法异构网络相对于LEACH(low-energy adaptive clustering hierarchy)算法同构网络的稳定周期延长了12.1%。采用无线通信模块nRF905射频芯片和TDJ-0825BKM1定向天线,在水稻田进行混合天线通信试验,测试了定向天线水平覆盖范围;在此基础上的网络模拟试验结果表明,基于该算法的通信网络稳定周期比值相比于LEACH、LEACH-E(LEACH-energy adaptive and uneven cluster)、DEEC(design of energy efficient clustering)、EADC(energy aware data-gathering cluster-heads)4种算法分别提高了46%、47%、58%、11%。该研究可为大面积水稻田无线传感器网络组网进行环境参数实时监测提供理论参考。
