The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machinin...The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machining. In order to smooth the connection of adjacent arcs and shorten the NC machining program, an interpolation method based on Chebyshev theory of function approximation is proposed here. According to the analysis of the interpolation error, the algorithm is simple and with high precision. By this way the fewest interpolating circular arc segments can be got, and the manufacture requirement is satisfied with the circular arc interpolating curves.展开更多
Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied...Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.展开更多
This paper focuses on the interaction between a micro/nano curved surface and a particle located inside the surface (hereafter abbreviated as in-surface-particle).Based on the exponential pair potential (namely 1/R2k)...This paper focuses on the interaction between a micro/nano curved surface and a particle located inside the surface (hereafter abbreviated as in-surface-particle).Based on the exponential pair potential (namely 1/R2k) between particles,the interaction potential between the micro/nano curved surface and the in-surface-particle is derived.The following results are shown:(a) For an even number of exponents in the pair potential,the interaction potential between the micro/nano curved surface and the in-surface-particle can be expressed as a unified function of the mean curvature and Gaussian curvature of the curved surface;(b) the curvatures and the gradients of curvatures of the micro/nano curved surface are the essential factors that dominate the driving force acting on the particle.展开更多
Background:A colonoscopy can detect colorectal diseases,including cancers,polyps,and inflammatory bowel diseases.A computer-aided diagnosis(CAD)system using deep convolutional neural networks(CNNs)that can recognize a...Background:A colonoscopy can detect colorectal diseases,including cancers,polyps,and inflammatory bowel diseases.A computer-aided diagnosis(CAD)system using deep convolutional neural networks(CNNs)that can recognize anatomical locations during a colonoscopy could efficiently assist practitioners.We aimed to construct a CAD system using a CNN to distinguish colorectal images from parts of the cecum,ascending colon,transverse colon,descending colon,sigmoid colon,and rectum.Method:We constructed a CNN by training of 9,995 colonoscopy images and tested its performance by 5,121 independent colonoscopy images that were categorized according to seven anatomical locations:the terminal ileum,the cecum,ascending colon to transverse colon,descending colon to sigmoid colon,the rectum,the anus,and indistinguishable parts.We examined images taken during total colonoscopy performed between January 2017 and November 2017 at a single center.We evaluated the concordance between the diagnosis by endoscopists and those by the CNN.The main outcomes of the study were the sensitivity and specificity of the CNN for the anatomical categorization of colonoscopy images.Results:The constructed CNN recognized anatomical locations of colonoscopy images with the following areas under the curves:0.979 for the terminal ileum;0.940 for the cecum;0.875 for ascending colon to transverse colon;0.846 for descending colon to sigmoid colon;0.835 for the rectum;and 0.992 for the anus.During the test process,the CNN system correctly recognized 66.6%of images.Conclusion:We constructed the new CNN system with clinically relevant performance for recognizing anatomical locations of colonoscopy images,which is the first step in constructing a CAD system that will support us during colonoscopy and provide an assurance of the quality of the colonoscopy procedure.展开更多
文摘The transverse section of piston skirt is not a standard circle and is with high precision. So the section curve should be interpolated through the high accuracy method of circular arc interpolation before NC machining. In order to smooth the connection of adjacent arcs and shorten the NC machining program, an interpolation method based on Chebyshev theory of function approximation is proposed here. According to the analysis of the interpolation error, the algorithm is simple and with high precision. By this way the fewest interpolating circular arc segments can be got, and the manufacture requirement is satisfied with the circular arc interpolating curves.
文摘Experimental study was carried out on the in-plane bending behavior of glass plates without lateral supports, and the effects of the factors, such as height-to-span ratio, on the stability of glass panels were studied. Results show that the in-plane bending glass plates with both ends simply supported and their upper edge free lose overall stability under loads, which belongs to the limit-point type of instability. It is found that the buckling load increases linearly with the increase of height-to-span ratio of the glass plates. The lateral stress of in-plane bending glass plates without lateral supports increases linearly under loads; while the large-area stress increases nonlinearly and the lateral stress is not the controlling factor of instability. In finite element analysis, the first buckling mode is regarded as the initial imperfection and imposed on the model as 1/1000 of the span of the components. The numerical buckling load according to the theory of large deflection is less than the experiment result, which is more conservative and can provide some reference for design. For the design method, when the in-plane load is imposed on the glass plate, its lateral strength and the deflection should be verified. Considering the stability of the in-plane bending glass plate without reliable lateral support, buckling is another possible failure mode and calls for verification.
基金supported by the National Natural Sciences Foundation of China (Grant Nos.11072125 and 10872114)the Natural Science Foundation of Jiangsu province (Grant No. SBK201140044)
文摘This paper focuses on the interaction between a micro/nano curved surface and a particle located inside the surface (hereafter abbreviated as in-surface-particle).Based on the exponential pair potential (namely 1/R2k) between particles,the interaction potential between the micro/nano curved surface and the in-surface-particle is derived.The following results are shown:(a) For an even number of exponents in the pair potential,the interaction potential between the micro/nano curved surface and the in-surface-particle can be expressed as a unified function of the mean curvature and Gaussian curvature of the curved surface;(b) the curvatures and the gradients of curvatures of the micro/nano curved surface are the essential factors that dominate the driving force acting on the particle.
文摘Background:A colonoscopy can detect colorectal diseases,including cancers,polyps,and inflammatory bowel diseases.A computer-aided diagnosis(CAD)system using deep convolutional neural networks(CNNs)that can recognize anatomical locations during a colonoscopy could efficiently assist practitioners.We aimed to construct a CAD system using a CNN to distinguish colorectal images from parts of the cecum,ascending colon,transverse colon,descending colon,sigmoid colon,and rectum.Method:We constructed a CNN by training of 9,995 colonoscopy images and tested its performance by 5,121 independent colonoscopy images that were categorized according to seven anatomical locations:the terminal ileum,the cecum,ascending colon to transverse colon,descending colon to sigmoid colon,the rectum,the anus,and indistinguishable parts.We examined images taken during total colonoscopy performed between January 2017 and November 2017 at a single center.We evaluated the concordance between the diagnosis by endoscopists and those by the CNN.The main outcomes of the study were the sensitivity and specificity of the CNN for the anatomical categorization of colonoscopy images.Results:The constructed CNN recognized anatomical locations of colonoscopy images with the following areas under the curves:0.979 for the terminal ileum;0.940 for the cecum;0.875 for ascending colon to transverse colon;0.846 for descending colon to sigmoid colon;0.835 for the rectum;and 0.992 for the anus.During the test process,the CNN system correctly recognized 66.6%of images.Conclusion:We constructed the new CNN system with clinically relevant performance for recognizing anatomical locations of colonoscopy images,which is the first step in constructing a CAD system that will support us during colonoscopy and provide an assurance of the quality of the colonoscopy procedure.
