The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes...The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes a novel videogrammetric method for full-field dynamic deformation measurement.A stereo matching method based on epipolar geometry constraint and topological constraint is presented to find the corresponding targets between stereo images.In addition,a new method based on affine transformation combined with adjacent closest point matching is developed,aiming to achieve fast and automatic tracking of targets in time-series images with large deformation.A calculation model for dynamic deformation parameters is established to obtain the displacement,sweep variable angle,and span variation.To verify the proposed method,a dynamic deformation measurement experiment is conducted on a variable-sweep wing model.The results indicate that the actual accuracy of the proposed method is approximately 0.02%of the measured area(e.g.,0.32 mm in a 1.6 m scale).During one morphing course,the sweep variable angle,the span variation and the displacement increase gradually,and then decrease.The maximum sweep variable angle is 36.6°,and the span variation is up to 101.13 mm.The overall configuration of the wing surface is effectively reconstructed under different morphing states.展开更多
AIM:To examine the feasibility and reliability of measuring global and segmental longitudinal strain(LS) compared to visual assessment of wall motion(WM).METHODS:Assessment of segmental(17 left ventricular segments) L...AIM:To examine the feasibility and reliability of measuring global and segmental longitudinal strain(LS) compared to visual assessment of wall motion(WM).METHODS:Assessment of segmental(17 left ventricular segments) LS using automatic function imaging(AFI) in 55 patients(60.0 ± 8.7 years,73% male) divided into 2 groups:groupⅠ included 35 patients with WM abnormalities and/or impaired ejection fraction and group Ⅱ included 20 patients with normal WM and ejection fraction.Visual analysis of WM abnormalities was performed using 2-dimensional echocardiography(2DE) and WM score was calculated.Both modalities were analyzed by one expert reader at 2 different sessions.RESULTS:Analysis of 935 left ventricular segments was completed in 94.1% and 96.3% by visual assessment and AFI,respectively.There was a strong positive linear relationship between the WM score and global LS in all patients.Intra-observer agreement for calculation of WM score was excellent for groupⅠ patients(kappa:0.97) and very good for group Ⅱ patients(kappa:0.92).Intra-observer agreement for AFI showed excellent agreement with very small mean difference in both groupⅠ and Ⅱ(-0.0 ± 2.3 and-0.0 ± 1.9,respectively).CONCLUSION:The interpretation of global and segmental LS using AFI is a more feasible and reliable technique for the quantification of myocardial deformation than visual assessment of WM scores.展开更多
Chronic functional mitral regurgitation(FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy(DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in...Chronic functional mitral regurgitation(FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy(DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle(LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy(CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome.展开更多
Users of the digital image correlation method are faced with the problem of poor operability,low repeatability,and lack of standardized specifications for spraying speckles.To solve the problem,the research proposed a...Users of the digital image correlation method are faced with the problem of poor operability,low repeatability,and lack of standardized specifications for spraying speckles.To solve the problem,the research proposed a rock deformation measurement method that obviates the need to spray speckles.A local binary model was established by using the local binary pattern(LBP)operator based on deep texture features on rock surfaces.The resulting LBP digital speckle pattern can substitute artificial speckle patterns and demonstrates high quality and strong applicability.Based on the LBP digital speckle pattern,the target tracking algorithm was employed to achieve non-contact measurement of the dynamic displacements of rocks.The feasibility and effectiveness of the algorithm in practical application were verified by conducting shear tests on granite and siltstone.Test results show that the deformation characteristics in the displacement nephograms are in line with the measured data pertaining to rock fracturing and conform to the basic characteristics of the shear failure of rocks.The deformation measurement method based on surface texture information can realize non-contact displacement measurement of rocks under conditions without speckles:this obviates the influence of the quality of sprayed speckles on the accuracy of the measurement of deformation.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12202282).
文摘The measurement of wing dynamic deformation in morphing aircraft is crucial for achieving closed-loop control and evaluating structural safety.For variable-sweep wings with active large deformation,this paper proposes a novel videogrammetric method for full-field dynamic deformation measurement.A stereo matching method based on epipolar geometry constraint and topological constraint is presented to find the corresponding targets between stereo images.In addition,a new method based on affine transformation combined with adjacent closest point matching is developed,aiming to achieve fast and automatic tracking of targets in time-series images with large deformation.A calculation model for dynamic deformation parameters is established to obtain the displacement,sweep variable angle,and span variation.To verify the proposed method,a dynamic deformation measurement experiment is conducted on a variable-sweep wing model.The results indicate that the actual accuracy of the proposed method is approximately 0.02%of the measured area(e.g.,0.32 mm in a 1.6 m scale).During one morphing course,the sweep variable angle,the span variation and the displacement increase gradually,and then decrease.The maximum sweep variable angle is 36.6°,and the span variation is up to 101.13 mm.The overall configuration of the wing surface is effectively reconstructed under different morphing states.
文摘AIM:To examine the feasibility and reliability of measuring global and segmental longitudinal strain(LS) compared to visual assessment of wall motion(WM).METHODS:Assessment of segmental(17 left ventricular segments) LS using automatic function imaging(AFI) in 55 patients(60.0 ± 8.7 years,73% male) divided into 2 groups:groupⅠ included 35 patients with WM abnormalities and/or impaired ejection fraction and group Ⅱ included 20 patients with normal WM and ejection fraction.Visual analysis of WM abnormalities was performed using 2-dimensional echocardiography(2DE) and WM score was calculated.Both modalities were analyzed by one expert reader at 2 different sessions.RESULTS:Analysis of 935 left ventricular segments was completed in 94.1% and 96.3% by visual assessment and AFI,respectively.There was a strong positive linear relationship between the WM score and global LS in all patients.Intra-observer agreement for calculation of WM score was excellent for groupⅠ patients(kappa:0.97) and very good for group Ⅱ patients(kappa:0.92).Intra-observer agreement for AFI showed excellent agreement with very small mean difference in both groupⅠ and Ⅱ(-0.0 ± 2.3 and-0.0 ± 1.9,respectively).CONCLUSION:The interpretation of global and segmental LS using AFI is a more feasible and reliable technique for the quantification of myocardial deformation than visual assessment of WM scores.
文摘Chronic functional mitral regurgitation(FMR) is a frequent finding of ischemic heart disease and dilated cardiomyopathy(DCM), associated with unfavourable prognosis. Several pathophysiologic mechanisms are involved in FMR, such as annular dilatation and dysfunction, left ventricle(LV) remodeling, dysfunction and dyssynchrony, papillary muscles displacement and dyssynchrony. The best therapeutic choice for FMR is still debated. When optimal medical treatment has already been set, a further option for cardiac resynchronization therapy(CRT) and/or surgical correction should be considered. CRT is able to contrast most of the pathophysiologic determinants of FMR by minimizing LV dyssynchrony through different mechanisms: Increasing closing forces, reducing tethering forces, reshaping annular geometry and function, correcting diastolic MR. Deformation imaging in terms of two-dimensional speckle tracking has been validated for LV dyssynchrony assessment. Radial speckle tracking and three-dimensional strain analysis appear to be the best methods to quantify intraventricular delay and to predict CRT-responders. Speckle-tracking echocardiography in patients with mitral valve regurgitation has been usually proposed for the assessment of LV and left atrial function. However it has also revealed a fundamental role of intraventricular dyssynchrony in determining FMR especially in DCM, rather than in ischemic cardiomyopathy in which MR severity seems to be more related to mitral valve deformation indexes. Furthermore speckle tracking allows the assessment of papillary muscle dyssynchrony. Therefore this technique can help to identify optimal candidates to CRT that will probably demonstrate a reduction in FMR degree and thus will experience a better outcome.
基金supported by the National Natural Science Foundation of China(No.52074123)the Natural Science Foundation of Hebei Province(Nos.E2022209143,E2021209148 and E2021209052).
文摘Users of the digital image correlation method are faced with the problem of poor operability,low repeatability,and lack of standardized specifications for spraying speckles.To solve the problem,the research proposed a rock deformation measurement method that obviates the need to spray speckles.A local binary model was established by using the local binary pattern(LBP)operator based on deep texture features on rock surfaces.The resulting LBP digital speckle pattern can substitute artificial speckle patterns and demonstrates high quality and strong applicability.Based on the LBP digital speckle pattern,the target tracking algorithm was employed to achieve non-contact measurement of the dynamic displacements of rocks.The feasibility and effectiveness of the algorithm in practical application were verified by conducting shear tests on granite and siltstone.Test results show that the deformation characteristics in the displacement nephograms are in line with the measured data pertaining to rock fracturing and conform to the basic characteristics of the shear failure of rocks.The deformation measurement method based on surface texture information can realize non-contact displacement measurement of rocks under conditions without speckles:this obviates the influence of the quality of sprayed speckles on the accuracy of the measurement of deformation.