In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have differ...In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have different orientations.Existing OBB object detection for remote sensing images,although making good progress,mainly focuses on directional modeling,while less consideration is given to the size of the object as well as the problem of missed detection.In this study,a method based on improved YOLOv8 was proposed for detecting oriented objects in remote sensing images,which can improve the detection precision of oriented objects in remote sensing images.Firstly,the ResCBAMG module was innovatively designed,which could better extract channel and spatial correlation information.Secondly,the innovative top-down feature fusion layer network structure was proposed in conjunction with the Efficient Channel Attention(ECA)attention module,which helped to capture inter-local cross-channel interaction information appropriately.Finally,we introduced an innovative ResCBAMG module between the different C2f modules and detection heads of the bottom-up feature fusion layer.This innovative structure helped the model to better focus on the target area.The precision and robustness of oriented target detection were also improved.Experimental results on the DOTA-v1.5 dataset showed that the detection Precision,mAP@0.5,and mAP@0.5:0.95 metrics of the improved model are better compared to the original model.This improvement is effective in detecting small targets and complex scenes.展开更多
In order to simulate the real growing process, a new type of knowledge network growth mechanism based on local world connectivity is constructed. By the mean-field method, theoretical prediction of the degree distribu...In order to simulate the real growing process, a new type of knowledge network growth mechanism based on local world connectivity is constructed. By the mean-field method, theoretical prediction of the degree distribution of the knowledge network is given, which is verified by Matlab simulations. When the new added node＇s local world size is very small, the degree distribution of the knowledge network approximately has the property of scale-free. When the new added node＇s local world size is not very small, the degree distribution transforms from pure power-law to the power-law with an exponential tailing. And the scale-free index increases as the number of new added edges decreases and the tunable parameters increase. Finally, comparisons of some knowledge indices in knowledge networks generated by the local world mechanism and the global mechanism are given. In the long run, compared with the global mechanism, the local world mechanism leads the average knowledge levels to slower growth and brings homogenous phenomena.展开更多
In this paper, we give a Z 2 index theory of generalized critical point. By this theory we get a sufficient condition on the existing result of a class functional, as an example we give a new result that the equa...In this paper, we give a Z 2 index theory of generalized critical point. By this theory we get a sufficient condition on the existing result of a class functional, as an example we give a new result that the equation-Δu+u=｜u｜ p-1 u, x∈R N,(1)has infinite solutions.展开更多
Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in e...Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in eastern North America, were selected to explore relationship between the northward distribution of temperate tree species and climatic factors. For each species, more than 30 sites at their north limits of distribution were obtained from their distribution maps, and 11 climatic indices at the north limits were computed. The standardized standard deviation (SD) method, which compares the magnitude of variance of climatic indices, was used to detect which climatic parameter was the most important for explaining northward distribution of these species. We presume that the climatic parameter that has the smallest variance at the north limit would be assigned as the dominant climatic factor for limiting the distribution of this species. The results derived from the standardized SD method indicated that the SD value of warmth index (WI) and/or annual biotemperature (ABT) were the smallest among the 11 climatic indices. Since both WI and ABT represent growing season temperature, it suggested that growing season temperature was the most important climatic factor for explaining the northward distribution of these temperate tree species. The relationships between several climatic indices, WI, coldness index (CI), annual precipitation (AP), annual range of temperature (ART) and humid/arid index were also analyzed. As a result, at the north limits of all these species, both WI and CI decreased with an increase of AP, and CI increased with an increase of ART. Besides growing season temperature, precipitation and climatic continentality also have influence on the northward distribution of the temperate trees in eastern North America.展开更多
Objective The optimal antithrombotic regimen for patients on oral anticoagulation （OAC） after acute coronary syndrome （ACS） and percutaneous coronary intervention （PCI） remains debated. This study sought to eval...Objective The optimal antithrombotic regimen for patients on oral anticoagulation （OAC） after acute coronary syndrome （ACS） and percutaneous coronary intervention （PCI） remains debated. This study sought to evaluate the efficacy and safety of OAC plus clopidogrel with or without aspirin in a real-world setting. Methods We retrospectively analyzed data from an international, multi-center registry be- tween 2003 and 2014 （n = 15,401）. Patients with ACS and receiving OAC after PCI were screened. The composite primary endpoint was 1-year all-cause death, re-infarction, or severe bleeding. Results The final analysis enrolled 642 patients including 62 patients （9.7%） with OAC and clopidogrel （dual therapy）, and 580 patients （90.3%） with the combination of aspirin, OAC and clopidogrel （triple therapy）. Pa- tients on triple therapy were more often female and were more likely to have comorbidities. There was no significant difference regarding the primary end point between dual therapy with triple therapy patients [17.74% vs. 17.24%; unadjusted hazard ratio （HR）： 1.035; 95% confi- dence interval （CI）： 0.556-1.929; adjusted HR： 1.026; 95% CI： 0.544-1.937]. However, the re-infarction rate was significantly higher in dual therapy than triple therapy patients （14.52% vs. 5.34%; unadjusted HR： 2.807; 95% CI： 1.329-5.928; adjusted HR： 2.333; 95% CI： 1.078-5.047）. In addition, there was no difference between two regimes in all-cause death and severe bleeding. Conclusions In real-life patients with ACS following PCI and with an indication of OAC, triple therapy was not associated with an increased rate of adverse out- comes compared to dual therapy. Moreover, it decreased risk of re-infarction and did not increase risk of severe bleeding.展开更多
The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,un...The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,under a relatively high normal stress,normal stress and the coefficient of structural roughness are the most important factors affecting the mechanical interface characteristics. The relationship between shear stress and shear displacement of the soil-structure interface is a hyperbolic curve with high regression accuracy. Based on our experimental results,a nonlinear elastic con-stitutive model of the soil-structure interface under relatively high normal stress is established with a definite physical meaning for its parameters. The model can predict the strain hardening behavior of the soil during the shearing process. The results show an encouraging agreement with experimental data from direct shear tests.展开更多
文摘In the study of oriented bounding boxes(OBB)object detection in high-resolution remote sensing images,the problem of missed and wrong detection of small targets occurs because the targets are too small and have different orientations.Existing OBB object detection for remote sensing images,although making good progress,mainly focuses on directional modeling,while less consideration is given to the size of the object as well as the problem of missed detection.In this study,a method based on improved YOLOv8 was proposed for detecting oriented objects in remote sensing images,which can improve the detection precision of oriented objects in remote sensing images.Firstly,the ResCBAMG module was innovatively designed,which could better extract channel and spatial correlation information.Secondly,the innovative top-down feature fusion layer network structure was proposed in conjunction with the Efficient Channel Attention(ECA)attention module,which helped to capture inter-local cross-channel interaction information appropriately.Finally,we introduced an innovative ResCBAMG module between the different C2f modules and detection heads of the bottom-up feature fusion layer.This innovative structure helped the model to better focus on the target area.The precision and robustness of oriented target detection were also improved.Experimental results on the DOTA-v1.5 dataset showed that the detection Precision,mAP@0.5,and mAP@0.5:0.95 metrics of the improved model are better compared to the original model.This improvement is effective in detecting small targets and complex scenes.
基金The National Natural Science Foundation of China(No70571013,70973017)Program for New Century Excellent Talentsin University (NoNCET-06-0471)Human Social Science Fund Project ofMinistry of Education (No09YJA630020)
文摘In order to simulate the real growing process, a new type of knowledge network growth mechanism based on local world connectivity is constructed. By the mean-field method, theoretical prediction of the degree distribution of the knowledge network is given, which is verified by Matlab simulations. When the new added node＇s local world size is very small, the degree distribution of the knowledge network approximately has the property of scale-free. When the new added node＇s local world size is not very small, the degree distribution transforms from pure power-law to the power-law with an exponential tailing. And the scale-free index increases as the number of new added edges decreases and the tunable parameters increase. Finally, comparisons of some knowledge indices in knowledge networks generated by the local world mechanism and the global mechanism are given. In the long run, compared with the global mechanism, the local world mechanism leads the average knowledge levels to slower growth and brings homogenous phenomena.
文摘In this paper, we give a Z 2 index theory of generalized critical point. By this theory we get a sufficient condition on the existing result of a class functional, as an example we give a new result that the equation-Δu+u=｜u｜ p-1 u, x∈R N,(1)has infinite solutions.
文摘Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in eastern North America, were selected to explore relationship between the northward distribution of temperate tree species and climatic factors. For each species, more than 30 sites at their north limits of distribution were obtained from their distribution maps, and 11 climatic indices at the north limits were computed. The standardized standard deviation (SD) method, which compares the magnitude of variance of climatic indices, was used to detect which climatic parameter was the most important for explaining northward distribution of these species. We presume that the climatic parameter that has the smallest variance at the north limit would be assigned as the dominant climatic factor for limiting the distribution of this species. The results derived from the standardized SD method indicated that the SD value of warmth index (WI) and/or annual biotemperature (ABT) were the smallest among the 11 climatic indices. Since both WI and ABT represent growing season temperature, it suggested that growing season temperature was the most important climatic factor for explaining the northward distribution of these temperate tree species. The relationships between several climatic indices, WI, coldness index (CI), annual precipitation (AP), annual range of temperature (ART) and humid/arid index were also analyzed. As a result, at the north limits of all these species, both WI and CI decreased with an increase of AP, and CI increased with an increase of ART. Besides growing season temperature, precipitation and climatic continentality also have influence on the northward distribution of the temperate trees in eastern North America.
文摘Objective The optimal antithrombotic regimen for patients on oral anticoagulation （OAC） after acute coronary syndrome （ACS） and percutaneous coronary intervention （PCI） remains debated. This study sought to evaluate the efficacy and safety of OAC plus clopidogrel with or without aspirin in a real-world setting. Methods We retrospectively analyzed data from an international, multi-center registry be- tween 2003 and 2014 （n = 15,401）. Patients with ACS and receiving OAC after PCI were screened. The composite primary endpoint was 1-year all-cause death, re-infarction, or severe bleeding. Results The final analysis enrolled 642 patients including 62 patients （9.7%） with OAC and clopidogrel （dual therapy）, and 580 patients （90.3%） with the combination of aspirin, OAC and clopidogrel （triple therapy）. Pa- tients on triple therapy were more often female and were more likely to have comorbidities. There was no significant difference regarding the primary end point between dual therapy with triple therapy patients [17.74% vs. 17.24%; unadjusted hazard ratio （HR）： 1.035; 95% confi- dence interval （CI）： 0.556-1.929; adjusted HR： 1.026; 95% CI： 0.544-1.937]. However, the re-infarction rate was significantly higher in dual therapy than triple therapy patients （14.52% vs. 5.34%; unadjusted HR： 2.807; 95% CI： 1.329-5.928; adjusted HR： 2.333; 95% CI： 1.078-5.047）. In addition, there was no difference between two regimes in all-cause death and severe bleeding. Conclusions In real-life patients with ACS following PCI and with an indication of OAC, triple therapy was not associated with an increased rate of adverse out- comes compared to dual therapy. Moreover, it decreased risk of re-infarction and did not increase risk of severe bleeding.
基金Projects 50534040 supported by the National Natural Science Foundation of China2002CB412704 by the Major State Basic Research and Development Program of China
文摘The shear characteristics of soil-structure interfaces with different roughness are studied systematically by us-ing the DRS-1 high normal stress and residual shear apparatus. The experimental results indicate that,under a relatively high normal stress,normal stress and the coefficient of structural roughness are the most important factors affecting the mechanical interface characteristics. The relationship between shear stress and shear displacement of the soil-structure interface is a hyperbolic curve with high regression accuracy. Based on our experimental results,a nonlinear elastic con-stitutive model of the soil-structure interface under relatively high normal stress is established with a definite physical meaning for its parameters. The model can predict the strain hardening behavior of the soil during the shearing process. The results show an encouraging agreement with experimental data from direct shear tests.
