Spatial angle measurement, especially the measurement of horizontal and vertical angle, is a basic method used for industrial large-scale coordinate measurement. As main equipments in use, both theodolites and laser t...Spatial angle measurement, especially the measurement of horizontal and vertical angle, is a basic method used for industrial large-scale coordinate measurement. As main equipments in use, both theodolites and laser trackers can provide very high accuracy for spatial angle measurement. However, their industrial applications are limited by low level of automation and poor parallelism. For the purpose of improving measurement efficiency, a lot of studies have been conducted and several alternative methods have been proposed. Unfortunately, all these means are either low precision or too expensive. In this paper, a novel method of spatial angle measurement based on two rotating planar laser beams is proposed and demonstrated. Photoelectric receivers placed on measured points are used to receive the rotating planner laser signals transmitted by laser transmitters. The scanning time intervals of laser planes were measured, and then measured point＇s horizontal/vertical angles can be calculated. Laser plane＇s angle parameters are utilized to establish the abstract geometric model of transmitter. Calculating formulas of receiver＇s horizontal/vertical angles have been derived. Measurement equations＇ solvability conditions and judgment method of imaginary solutions are also presented after analyzing. Proposed method for spatial angle measurement is experimentally verified through a platform consisting of one laser transmitter and one optical receiver. The transmitters used in new method are only responsible for providing rotating light plane signals carrying angle information. Receivers automatically measure scanning time of laser planes and upload data to the workstation to calculate horizontal angle and vertical angle. Simultaneous measurement of multiple receivers can be realized since there is no human intervention in measurement process .Spatial angle measurement result indicates that the repeatable accuracy of new method is better than 10＂. Proposed method can improve measurement＇s automation degree and speed while ensuring measurement accuracy.展开更多
The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both...The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties.In addition,a relatively weak speckle reduction particularly in distributed media was reported in the related literatures.In this work,an improved SMB filtering strategy is proposed considering the aforementioned deficiencies.First,the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition.In addition,an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction.We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band Pol SAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR(AIRSAR)system.展开更多
Aiming at the specific cases existing in spatial angles calculation the paper investigates five types of them： lines in specific orientations, planes in specific orientations, two lines defining a plane and angles be...Aiming at the specific cases existing in spatial angles calculation the paper investigates five types of them： lines in specific orientations, planes in specific orientations, two lines defining a plane and angles between them, orientations and relevant parameters of a line lying on a plane, and orientations and relevant parameters of a plane passing through a line. The results are presented. The strategy presented provides a firm theoretic basis for the application of the new method of spatial angles calculations.展开更多
The QRS-T angle,as an index of noninvasive cardioelectric vector,is closely related to the change of heart structure and function.There are different methedologies to measure the QRS-T angle,which can be roughly divid...The QRS-T angle,as an index of noninvasive cardioelectric vector,is closely related to the change of heart structure and function.There are different methedologies to measure the QRS-T angle,which can be roughly dividedinto two types:plane angle and space angle.Studies show that the influence factors include two aspects of physiology and pathology of the angle,in pathological ways,the disease such as myocardial hypertrophy,myocardial ischemia,hypertension,ventricular arrhythmia has larger clinical significance.In recent years,the research on the risk stratification of the QRS-T angle on sudden death has made great progress,but there are still some disputes about whether the space angle can be replaced by the plane angle and the range of normal value and so on.展开更多
Tactical Ballistic Missile(TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead(FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement ...Tactical Ballistic Missile(TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead(FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement logic.For conventional axi-symmetric warhead,dispersion is assumed to be normal with a standard deviation of 3~O.However,such information is not available in case of FGW.Hence,a set of experiments are conducted to determine the dispersion of fragments.The experiments are conducted with a specific configuration of FGW in an identical arena to quantify the scatter and then verified its applicability to other configurations having a range of L/D and C/M ratios,and contoured fragmenting discs.From the experimental study,it is concluded that the scatter in projection angle follows normal distribution with a standard deviation of 0.75° at Chi-square significance level of 0.01(x_(0.99)~2).展开更多
A continuum thermodynamic model for how whirls can transform into thermal energy-forms determined by a functional relation for temperature is derived. This is used to describe how fishes maintain circulation in the va...A continuum thermodynamic model for how whirls can transform into thermal energy-forms determined by a functional relation for temperature is derived. This is used to describe how fishes maintain circulation in the vascular system, at very low temperatures.展开更多
针对小尺寸列车风管与折角塞门的检测问题,提出一种多尺度特征增强的YOLOv5s检测算法。首先在主干网络Backbone增加了一个大尺寸特征图输出分支,使用C2f(CSP bottleneck with 2 convolution and forward)模块丰富新增特征图的梯度流信息...针对小尺寸列车风管与折角塞门的检测问题,提出一种多尺度特征增强的YOLOv5s检测算法。首先在主干网络Backbone增加了一个大尺寸特征图输出分支,使用C2f(CSP bottleneck with 2 convolution and forward)模块丰富新增特征图的梯度流信息;然后在Neck部分使用自适应空间特征融合增强特征金字塔模型FPN (Feature Pyramid Network)的多尺度特征融合能力,并使用路径聚合模型PAN(Path Aggregation Network)提高目标定位能力;检测头Head拥有4种尺度的特征图,其中新增特征图的尺寸最大,用于增强小尺寸目标的检测能力。实验结果表明,多尺度特征增强的YOLOv5s比原来的YOLOv5s在平均精度mAP(mean Average Precision)上提升了1.5%,优于其他检测器,提升了小尺寸风管和折角塞门的检测能力。展开更多
A spatial channel propagation model is presented. Consider a uniform linear antenna （ULA） at the base station （BS） and narrowband signals transmitted at the mobile. In two types of propagating environments： indoo...A spatial channel propagation model is presented. Consider a uniform linear antenna （ULA） at the base station （BS） and narrowband signals transmitted at the mobile. In two types of propagating environments： indoor and outdoor, performance of low spatial correlation is investigated and some results are provided, which are significant to an,3. lyze the performance of diversity systems and configuration of army. The results also show that the configuration of array with either smaller angular spread or bigger angle of arrival （AOA） dominates the impact on spatial correlation, and that increasing angular spread or decreasing AOA diminishes, or even eliminates this impact.展开更多
基金supported by Key Program of National Natural Science Foundation of China (Grant No. 50735003)
文摘Spatial angle measurement, especially the measurement of horizontal and vertical angle, is a basic method used for industrial large-scale coordinate measurement. As main equipments in use, both theodolites and laser trackers can provide very high accuracy for spatial angle measurement. However, their industrial applications are limited by low level of automation and poor parallelism. For the purpose of improving measurement efficiency, a lot of studies have been conducted and several alternative methods have been proposed. Unfortunately, all these means are either low precision or too expensive. In this paper, a novel method of spatial angle measurement based on two rotating planar laser beams is proposed and demonstrated. Photoelectric receivers placed on measured points are used to receive the rotating planner laser signals transmitted by laser transmitters. The scanning time intervals of laser planes were measured, and then measured point＇s horizontal/vertical angles can be calculated. Laser plane＇s angle parameters are utilized to establish the abstract geometric model of transmitter. Calculating formulas of receiver＇s horizontal/vertical angles have been derived. Measurement equations＇ solvability conditions and judgment method of imaginary solutions are also presented after analyzing. Proposed method for spatial angle measurement is experimentally verified through a platform consisting of one laser transmitter and one optical receiver. The transmitters used in new method are only responsible for providing rotating light plane signals carrying angle information. Receivers automatically measure scanning time of laser planes and upload data to the workstation to calculate horizontal angle and vertical angle. Simultaneous measurement of multiple receivers can be realized since there is no human intervention in measurement process .Spatial angle measurement result indicates that the repeatable accuracy of new method is better than 10＂. Proposed method can improve measurement＇s automation degree and speed while ensuring measurement accuracy.
基金Project(2012CB957702) supported by the National Basic Research Program of ChinaProjects(41590854,41431070,41274024,41321063) supported by the National Natural Science Foundation of ChinaProject(Y205771077) supported by the Hundred Talents Program of the Chinese Academy of Sciences
文摘The scattering-model-based(SMB)speckle filtering for polarimetric SAR(Pol SAR)data is reasonably effective in preserving dominant scattering mechanisms.However,the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties.In addition,a relatively weak speckle reduction particularly in distributed media was reported in the related literatures.In this work,an improved SMB filtering strategy is proposed considering the aforementioned deficiencies.First,the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition.In addition,an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction.We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band Pol SAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR(AIRSAR)system.
基金Supported by National Natural Science Foundation Council of Henan Province (011106300)
文摘Aiming at the specific cases existing in spatial angles calculation the paper investigates five types of them： lines in specific orientations, planes in specific orientations, two lines defining a plane and angles between them, orientations and relevant parameters of a line lying on a plane, and orientations and relevant parameters of a plane passing through a line. The results are presented. The strategy presented provides a firm theoretic basis for the application of the new method of spatial angles calculations.
文摘The QRS-T angle,as an index of noninvasive cardioelectric vector,is closely related to the change of heart structure and function.There are different methedologies to measure the QRS-T angle,which can be roughly dividedinto two types:plane angle and space angle.Studies show that the influence factors include two aspects of physiology and pathology of the angle,in pathological ways,the disease such as myocardial hypertrophy,myocardial ischemia,hypertension,ventricular arrhythmia has larger clinical significance.In recent years,the research on the risk stratification of the QRS-T angle on sudden death has made great progress,but there are still some disputes about whether the space angle can be replaced by the plane angle and the range of normal value and so on.
文摘Tactical Ballistic Missile(TBM) class target neutralization by the fragment spray of a Fragment Generator Warhead(FGW) calls for quantification of fragment projection angle scatter to finalize the end game engagement logic.For conventional axi-symmetric warhead,dispersion is assumed to be normal with a standard deviation of 3~O.However,such information is not available in case of FGW.Hence,a set of experiments are conducted to determine the dispersion of fragments.The experiments are conducted with a specific configuration of FGW in an identical arena to quantify the scatter and then verified its applicability to other configurations having a range of L/D and C/M ratios,and contoured fragmenting discs.From the experimental study,it is concluded that the scatter in projection angle follows normal distribution with a standard deviation of 0.75° at Chi-square significance level of 0.01(x_(0.99)~2).
文摘A continuum thermodynamic model for how whirls can transform into thermal energy-forms determined by a functional relation for temperature is derived. This is used to describe how fishes maintain circulation in the vascular system, at very low temperatures.
文摘针对小尺寸列车风管与折角塞门的检测问题,提出一种多尺度特征增强的YOLOv5s检测算法。首先在主干网络Backbone增加了一个大尺寸特征图输出分支,使用C2f(CSP bottleneck with 2 convolution and forward)模块丰富新增特征图的梯度流信息;然后在Neck部分使用自适应空间特征融合增强特征金字塔模型FPN (Feature Pyramid Network)的多尺度特征融合能力,并使用路径聚合模型PAN(Path Aggregation Network)提高目标定位能力;检测头Head拥有4种尺度的特征图,其中新增特征图的尺寸最大,用于增强小尺寸目标的检测能力。实验结果表明,多尺度特征增强的YOLOv5s比原来的YOLOv5s在平均精度mAP(mean Average Precision)上提升了1.5%,优于其他检测器,提升了小尺寸风管和折角塞门的检测能力。
基金This project was supported by the National High-Tech Research and Development Program (2002AA123032).
文摘A spatial channel propagation model is presented. Consider a uniform linear antenna （ULA） at the base station （BS） and narrowband signals transmitted at the mobile. In two types of propagating environments： indoor and outdoor, performance of low spatial correlation is investigated and some results are provided, which are significant to an,3. lyze the performance of diversity systems and configuration of army. The results also show that the configuration of array with either smaller angular spread or bigger angle of arrival （AOA） dominates the impact on spatial correlation, and that increasing angular spread or decreasing AOA diminishes, or even eliminates this impact.
