In view of the problems existing in GPS, a non-gyroscope DR is introduced. The operating principle and the algorithm of the GPS/DR device are also presented. By operating measured data synthetically, linear observatio...In view of the problems existing in GPS, a non-gyroscope DR is introduced. The operating principle and the algorithm of the GPS/DR device are also presented. By operating measured data synthetically, linear observation equations are obtained for the information fusion algorithm. This approach avoids model error due to linearizing nonlinear observation equations in the conventional algorithm, so that the stability of information fusion algorithm is improved and computation expenses are reduced. Field running experiments show that satisfactory accuracy can be obtained by the proposed navigation model and algorithm for the non-gyroscope GPS/DR device.展开更多
Because of the large-scale integration of wind power,the dynamic characteristics of power system have many uncertain effects.Based on deterministic analysis methods,traditional on-line security assessment system canno...Because of the large-scale integration of wind power,the dynamic characteristics of power system have many uncertain effects.Based on deterministic analysis methods,traditional on-line security assessment system cannot quantitatively estimate the actual operating conditions of the power system for only considering the most serious and credible accidents.Therefore,the risk theory is introduced into an on-line security assessment system and then an on-line risk assessment system for wind power is designed and implemented by combining with the dynamic security assessment system.Based on multiple data integration,the wind power disturbance probability is available and the security assessment of the power grid can obtain security indices in different aspects.The operating risk index is an expectation of severity,computed by summing up all the products of the result probability and its severity.Analysis results are reported to the dispatchers in on-line environment,while the comprehensive weak links are automatically provided to the power dispatching center.The risk assessment system in operation can verify the reasonableness of the system.展开更多
目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中...目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中男19例,女80例。均行单纯后路长节段(固定椎体≥4个)固定融合手术,术后随访至少满2年。测量并记录所有患者术前、术后3个月及末次随访时的脊柱-骨盆参数。在脊柱全长侧位X线片上,将经外耳道口垂线定义为W-line,根据W-line不同位置分为A组、B组及C组。测量术后3个月时W-line到S1后上角水平距离(WSD)及W-line到股骨头中心连线中点的水平距离(WHD),将W-line位置进行数值转化(the numeric value of W-line,N-W-line):N-W-line=WHD/WSD。W-line位于参考点前方数值为正,反之为负。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析得出N-W-line临界值。三组患者参数进行方差分析,应用Kaplan-Meier曲线分析非PJF生存时间。结果:ROC曲线分析得出术后3个月N-W-line临界值为±0.78[敏感度=75%,特异度=75.9%,曲线下面积(the area under the curve,AUC)=0.736,P=0.003]。A组32例,N-W-line>0.78;B组49例,-0.78≤N-W-line≤0.78;C组18例,N-W-line<-0.78。A组患者骨盆入射角(pelvic incidence,PI)最小(P<0.05),术后3个月矢状面平衡距(P<0.001)、T1骨盆角(P<0.001)及骨盆腰椎匹配度(P<0.001)均显著小于其他两组患者。但随访中,A、B及C组分别有12例、3例及1例患者出现PJF,A组患者PJF发生率显著高于其他两组(12/32 vs 3/49 vs 1/18,P<0.001)。此外,A组患者非PJF生存时间显著低于其他两组患者(P=0.005,Log-rank检验)。B、C组患者W-line位置逐渐前移,脊柱-骨盆矢状位参数逐渐增大,但术后PJF发生率显著降低。结论:ASD患者矫形术后早期W-line位置可有效预测PJF发生。矫形手术后W-line偏后或过度偏前,术后随访中PJF发生率显著增加,矫形术后躯干呈轻度前屈为最佳。展开更多
In order to take full advantage of federated filter in fault-tolerant design of integrated navigation system, the limitation of fault detection algorithm for gradual changing fault detection and the poor fault toleran...In order to take full advantage of federated filter in fault-tolerant design of integrated navigation system, the limitation of fault detection algorithm for gradual changing fault detection and the poor fault tolerance of global optimal fusion algorithm are the key problems to deal with. Based on theoretical analysis of the influencing factors of federated filtering fault tolerance, global fault-tolerant fusion algorithm and information sharing algorithm are proposed based on fuzzy assessment. It achieves intelligent fault-tolerant structure with two-stage and feedback, including real-time fault detection in sub-filters, and fault-tolerant fusion and information sharing in main filter. The simulation results demonstrate that the algorithm can effectively improve fault-tolerant ability and ensure relatively high positioning precision of integrated navigation system when a subsystem having gradual changing fault.展开更多
【目的】煤矿井下普遍存在低照度、弱纹理和结构化的特征退化场景,导致视觉SLAM(visual simultaneous localization and mapping)系统面临有效特征不足或误匹配率高的问题,严重制约了其定位的准确性和鲁棒性。【方法】提出一种基于边缘...【目的】煤矿井下普遍存在低照度、弱纹理和结构化的特征退化场景,导致视觉SLAM(visual simultaneous localization and mapping)系统面临有效特征不足或误匹配率高的问题,严重制约了其定位的准确性和鲁棒性。【方法】提出一种基于边缘感知增强的视觉SLAM方法。首先,构建了边缘感知约束的低光图像增强模块。通过自适应尺度的梯度域引导滤波器优化Retinex算法,以获得纹理清晰光照均匀的图像,从而显著提升了在低光照和不均匀光照条件下特征提取性能。其次,在视觉里程计中构建了边缘感知增强的特征提取和匹配模块,通过点线特征融合策略有效增强了弱纹理和结构化场景中特征的可检测性和匹配准确性。具体使用边缘绘制线特征提取算法(edge drawing lines,EDLines)提取线特征,定向FAST和旋转BRIEF点特征提取算法(oriented fast and rotated brief,ORB)提取点特征,并利用基于网格运动统计(grid-based motion statistics,GMS)和比值测试匹配算法进行精确匹配。最后,将该方法与ORB-SLAM2、ORB-SLAM3在TUM数据集和煤矿井下实景数据集上进行了全面实验验证,涵盖图像增强、特征匹配和定位等多个环节。【结果和结论】结果表明:(1)在TUM数据集上的测试结果显示,所提方法与ORB-SLAM2相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了4%~38.46%、8.62%~50%;与ORB-SLAM3相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了0~61.68%、3.63%~47.05%。(2)在煤矿井下实景实验中,所提方法的定位轨迹更接近于相机运动参考轨迹。(3)有效提高了视觉SLAM在煤矿井下特征退化场景中的准确性和鲁棒性,为视觉SLAM技术在煤矿井下的应用提供了技术解决方案。研究面向井下特征退化场景的视觉SLAM方法,对于推动煤矿井下移动式装备机器人化具有重要意义。展开更多
文摘In view of the problems existing in GPS, a non-gyroscope DR is introduced. The operating principle and the algorithm of the GPS/DR device are also presented. By operating measured data synthetically, linear observation equations are obtained for the information fusion algorithm. This approach avoids model error due to linearizing nonlinear observation equations in the conventional algorithm, so that the stability of information fusion algorithm is improved and computation expenses are reduced. Field running experiments show that satisfactory accuracy can be obtained by the proposed navigation model and algorithm for the non-gyroscope GPS/DR device.
基金supported by National High Technology Research and Development Program of China (863 Program) (No.2011AA05A118)
文摘Because of the large-scale integration of wind power,the dynamic characteristics of power system have many uncertain effects.Based on deterministic analysis methods,traditional on-line security assessment system cannot quantitatively estimate the actual operating conditions of the power system for only considering the most serious and credible accidents.Therefore,the risk theory is introduced into an on-line security assessment system and then an on-line risk assessment system for wind power is designed and implemented by combining with the dynamic security assessment system.Based on multiple data integration,the wind power disturbance probability is available and the security assessment of the power grid can obtain security indices in different aspects.The operating risk index is an expectation of severity,computed by summing up all the products of the result probability and its severity.Analysis results are reported to the dispatchers in on-line environment,while the comprehensive weak links are automatically provided to the power dispatching center.The risk assessment system in operation can verify the reasonableness of the system.
文摘目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中男19例,女80例。均行单纯后路长节段(固定椎体≥4个)固定融合手术,术后随访至少满2年。测量并记录所有患者术前、术后3个月及末次随访时的脊柱-骨盆参数。在脊柱全长侧位X线片上,将经外耳道口垂线定义为W-line,根据W-line不同位置分为A组、B组及C组。测量术后3个月时W-line到S1后上角水平距离(WSD)及W-line到股骨头中心连线中点的水平距离(WHD),将W-line位置进行数值转化(the numeric value of W-line,N-W-line):N-W-line=WHD/WSD。W-line位于参考点前方数值为正,反之为负。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析得出N-W-line临界值。三组患者参数进行方差分析,应用Kaplan-Meier曲线分析非PJF生存时间。结果:ROC曲线分析得出术后3个月N-W-line临界值为±0.78[敏感度=75%,特异度=75.9%,曲线下面积(the area under the curve,AUC)=0.736,P=0.003]。A组32例,N-W-line>0.78;B组49例,-0.78≤N-W-line≤0.78;C组18例,N-W-line<-0.78。A组患者骨盆入射角(pelvic incidence,PI)最小(P<0.05),术后3个月矢状面平衡距(P<0.001)、T1骨盆角(P<0.001)及骨盆腰椎匹配度(P<0.001)均显著小于其他两组患者。但随访中,A、B及C组分别有12例、3例及1例患者出现PJF,A组患者PJF发生率显著高于其他两组(12/32 vs 3/49 vs 1/18,P<0.001)。此外,A组患者非PJF生存时间显著低于其他两组患者(P=0.005,Log-rank检验)。B、C组患者W-line位置逐渐前移,脊柱-骨盆矢状位参数逐渐增大,但术后PJF发生率显著降低。结论:ASD患者矫形术后早期W-line位置可有效预测PJF发生。矫形手术后W-line偏后或过度偏前,术后随访中PJF发生率显著增加,矫形术后躯干呈轻度前屈为最佳。
基金supported by the National Natural Science Foundationof China (60902055)
文摘In order to take full advantage of federated filter in fault-tolerant design of integrated navigation system, the limitation of fault detection algorithm for gradual changing fault detection and the poor fault tolerance of global optimal fusion algorithm are the key problems to deal with. Based on theoretical analysis of the influencing factors of federated filtering fault tolerance, global fault-tolerant fusion algorithm and information sharing algorithm are proposed based on fuzzy assessment. It achieves intelligent fault-tolerant structure with two-stage and feedback, including real-time fault detection in sub-filters, and fault-tolerant fusion and information sharing in main filter. The simulation results demonstrate that the algorithm can effectively improve fault-tolerant ability and ensure relatively high positioning precision of integrated navigation system when a subsystem having gradual changing fault.
文摘【目的】煤矿井下普遍存在低照度、弱纹理和结构化的特征退化场景,导致视觉SLAM(visual simultaneous localization and mapping)系统面临有效特征不足或误匹配率高的问题,严重制约了其定位的准确性和鲁棒性。【方法】提出一种基于边缘感知增强的视觉SLAM方法。首先,构建了边缘感知约束的低光图像增强模块。通过自适应尺度的梯度域引导滤波器优化Retinex算法,以获得纹理清晰光照均匀的图像,从而显著提升了在低光照和不均匀光照条件下特征提取性能。其次,在视觉里程计中构建了边缘感知增强的特征提取和匹配模块,通过点线特征融合策略有效增强了弱纹理和结构化场景中特征的可检测性和匹配准确性。具体使用边缘绘制线特征提取算法(edge drawing lines,EDLines)提取线特征,定向FAST和旋转BRIEF点特征提取算法(oriented fast and rotated brief,ORB)提取点特征,并利用基于网格运动统计(grid-based motion statistics,GMS)和比值测试匹配算法进行精确匹配。最后,将该方法与ORB-SLAM2、ORB-SLAM3在TUM数据集和煤矿井下实景数据集上进行了全面实验验证,涵盖图像增强、特征匹配和定位等多个环节。【结果和结论】结果表明:(1)在TUM数据集上的测试结果显示,所提方法与ORB-SLAM2相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了4%~38.46%、8.62%~50%;与ORB-SLAM3相比,绝对轨迹误差、相对轨迹误差的均方根误差分别降低了0~61.68%、3.63%~47.05%。(2)在煤矿井下实景实验中,所提方法的定位轨迹更接近于相机运动参考轨迹。(3)有效提高了视觉SLAM在煤矿井下特征退化场景中的准确性和鲁棒性,为视觉SLAM技术在煤矿井下的应用提供了技术解决方案。研究面向井下特征退化场景的视觉SLAM方法,对于推动煤矿井下移动式装备机器人化具有重要意义。
