In this paper,a new method is presented for 3D motion estimation by image region correspon- dences using stereo cameras.Under the weak perspectivity assumption,we first employ the moment tensor theory(Cyganski and Orr...In this paper,a new method is presented for 3D motion estimation by image region correspon- dences using stereo cameras.Under the weak perspectivity assumption,we first employ the moment tensor theory(Cyganski and Orr)to compute the monocular affine transformations relating images taken by the same camera at different time instants and the binocular affine transformations relating images taken by different cameras at the same time instant.We then show that 3D motion can he recovered from these 2D transformations.A space-time fusion strategy is proposed to aim at robust results.No knowledge of point correspondences is required in the above processes and the computa- lions involved are linear.To find corresponding image regions,new affine invariants,which show stronger invariance,are derived in term of tensor contraction theory.Experiments on real motion images are conducted to verify the proposed method.展开更多
In this paper a new method of passive underwater TMA (target motion analysis) using data fusion is presented. The findings of this research are based on an understanding that there is a powerful sonar system that cons...In this paper a new method of passive underwater TMA (target motion analysis) using data fusion is presented. The findings of this research are based on an understanding that there is a powerful sonar system that consists of many types of sonar but with one own-ship, and that different target parameter measurements can be obtained simultaneously. For the analysis 3 data measurements, passive bearing, elevation and multipath time-delay, are used, which are divided into two groups: a group with estimates of two preliminary target parameter obtained by dealing with each group measurement independently, and a group where correlated estimates are sent to a fusion center where the correlation between two data groups are considered so that the passive underwater TMA is realized. Simulation results show that curves of parameter estimation errors obtained by using the data fusion have fast convergence and the estimation accuracy is noticeably improved. The TMA algorithm presented is verified and is of practical significance because it is easy to be realized in one ship.展开更多
Background: Multiple level anterior cervical discectomy and fusion (ACDF) is indicated for those who suffer from multilevel stenosis or compression of the spinal canal. It was reported that this intervention would unf...Background: Multiple level anterior cervical discectomy and fusion (ACDF) is indicated for those who suffer from multilevel stenosis or compression of the spinal canal. It was reported that this intervention would unfortunately lead to a loss of normal cervical range of motion (CROM). Although, fewer studies have demonstrated the exact impact of the procedure on CROM. In our study, short and midterm postoperative CROM was described. Methods: Ninety patients who underwent ACDF were followed up postoperatively for at least 3 months. Active CROM was measured in all patients preoperatively and in postoperative follow-ups by cervical spine X-rays in lateral dynamic view using Cobb’s angle method. Results: Unfortunately, postoperative CROM was significantly diminished. At the short-term (3 months) follow-up there was a great limitation in CROM. While an obvious increase in CROM at the midterm (6 months) follow-up was observed in flexion especially. The reduction in global ROM (calculated as preoperative global ROM – 6 months postoperative ROM) was 4.1 and the reduction rate (calculated as reduction ROM divided by preoperative ROM) was 9.5%. The recovery ROM (calculated as 6 months postoperative ROM – 1 month postoperative ROM) was 8.2. The recovery rate (calculated as recovery ROM divided by 1 month postoperative ROM) was 26.5%. Conclusion: Active CROM following multiple level ACDF was obviously diminished. The most affected motion after surgery was flexion. It was noticed that at the short-term follow-up CROM would be more limited while after further follow up CROM was obviously improved even in neck flexion motion.展开更多
Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field,...Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field, a method which fuses conventional data with unconventional data based on variation principle is presented. The fundamental is constructing a cost function that makes the value approach conventional data and the gradient approach unconventional data. Using this method, the conventional wind and the cloud motion wind are fused. The fused wind field has high resolu- tion. Its wind direction approaches cloud motion wind which indicates move direction of the synoptic system, and its velocity approaches conventional wind which indicates move velocity of the synoptic system. The wind field data are used for short-time forecast of severe convective weather location, which gets a good result.展开更多
文摘In this paper,a new method is presented for 3D motion estimation by image region correspon- dences using stereo cameras.Under the weak perspectivity assumption,we first employ the moment tensor theory(Cyganski and Orr)to compute the monocular affine transformations relating images taken by the same camera at different time instants and the binocular affine transformations relating images taken by different cameras at the same time instant.We then show that 3D motion can he recovered from these 2D transformations.A space-time fusion strategy is proposed to aim at robust results.No knowledge of point correspondences is required in the above processes and the computa- lions involved are linear.To find corresponding image regions,new affine invariants,which show stronger invariance,are derived in term of tensor contraction theory.Experiments on real motion images are conducted to verify the proposed method.
文摘In this paper a new method of passive underwater TMA (target motion analysis) using data fusion is presented. The findings of this research are based on an understanding that there is a powerful sonar system that consists of many types of sonar but with one own-ship, and that different target parameter measurements can be obtained simultaneously. For the analysis 3 data measurements, passive bearing, elevation and multipath time-delay, are used, which are divided into two groups: a group with estimates of two preliminary target parameter obtained by dealing with each group measurement independently, and a group where correlated estimates are sent to a fusion center where the correlation between two data groups are considered so that the passive underwater TMA is realized. Simulation results show that curves of parameter estimation errors obtained by using the data fusion have fast convergence and the estimation accuracy is noticeably improved. The TMA algorithm presented is verified and is of practical significance because it is easy to be realized in one ship.
文摘Background: Multiple level anterior cervical discectomy and fusion (ACDF) is indicated for those who suffer from multilevel stenosis or compression of the spinal canal. It was reported that this intervention would unfortunately lead to a loss of normal cervical range of motion (CROM). Although, fewer studies have demonstrated the exact impact of the procedure on CROM. In our study, short and midterm postoperative CROM was described. Methods: Ninety patients who underwent ACDF were followed up postoperatively for at least 3 months. Active CROM was measured in all patients preoperatively and in postoperative follow-ups by cervical spine X-rays in lateral dynamic view using Cobb’s angle method. Results: Unfortunately, postoperative CROM was significantly diminished. At the short-term (3 months) follow-up there was a great limitation in CROM. While an obvious increase in CROM at the midterm (6 months) follow-up was observed in flexion especially. The reduction in global ROM (calculated as preoperative global ROM – 6 months postoperative ROM) was 4.1 and the reduction rate (calculated as reduction ROM divided by preoperative ROM) was 9.5%. The recovery ROM (calculated as 6 months postoperative ROM – 1 month postoperative ROM) was 8.2. The recovery rate (calculated as recovery ROM divided by 1 month postoperative ROM) was 26.5%. Conclusion: Active CROM following multiple level ACDF was obviously diminished. The most affected motion after surgery was flexion. It was noticed that at the short-term follow-up CROM would be more limited while after further follow up CROM was obviously improved even in neck flexion motion.
基金The National Natural Science Foundation of China Youth Program(No.52108139)Hunan Provincial Natural Science Foundation Youth Program(No.2023JJ40290).
文摘Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field, a method which fuses conventional data with unconventional data based on variation principle is presented. The fundamental is constructing a cost function that makes the value approach conventional data and the gradient approach unconventional data. Using this method, the conventional wind and the cloud motion wind are fused. The fused wind field has high resolu- tion. Its wind direction approaches cloud motion wind which indicates move direction of the synoptic system, and its velocity approaches conventional wind which indicates move velocity of the synoptic system. The wind field data are used for short-time forecast of severe convective weather location, which gets a good result.
