The heated test pieces were treated with alternating magnetic field by self-made experimental facility firstly. And influences of magnetic treatment on microstructure densification of Diamond Saw Segments were studied...The heated test pieces were treated with alternating magnetic field by self-made experimental facility firstly. And influences of magnetic treatment on microstructure densification of Diamond Saw Segments were studied through hardness testing, ultrasonic testing, metallurgical structure and fracture pattern analysis by comparative method. The mechanism of magnetic treatment is analyzed and discussed in the end. The results show that the hardness of test pieces after magnetized are harder than before, that HRB hardness is improved by 3.58 on average. The sound path and amplitude of echo wave both decrease in test pieces after magnetized. The relative pad value of echo wave is regularly related with the microstructure densification, what is profound to further establish the regularity studying the degree of matrices densification using ultrasonic testing. The pores become few and pore shape gradually spheroidizing with the magnetic treatment, and matrices are more homogeneous and compact than the without by metallographic microscope. The degree of matrices densification is further improved after magnetized. The average crystal grain size is finer than the without, and the reason of grain refining is that densification of diamond saw blade improved. Magnetic treatment can act as one kind of effective technique to improve the microstructure densification of diamond saw segments.展开更多
A mathematical model of gear tooth profiles using the ellipse curve, whose curvature is convenient to control by changing the mathematical parameters as its line of action, was built based on the meshing theory. The e...A mathematical model of gear tooth profiles using the ellipse curve, whose curvature is convenient to control by changing the mathematical parameters as its line of action, was built based on the meshing theory. The equation of undercutting condition was derived from the model. A special epicycloidal tooth profile was also presented. An example gear drive with variation of the ellipse parameters was taken to illustrate the proposed method. The contact ratio of the gear drive designed by the proposed method was analyzed. A comparison of the property of the gear drive designed with the involute gear drive was also carried out. The results confirm that the proposed gear drive has higher contact ratio in comparison with the involute gear drive.展开更多
The heated test pieces of diamond segments were treated by alternating magnetic field,the influences of magnetic treatment on microstructure densification of diamond segments were studied through metallurgical structu...The heated test pieces of diamond segments were treated by alternating magnetic field,the influences of magnetic treatment on microstructure densification of diamond segments were studied through metallurgical structure analysis.The experiment results indicated that,the densification of diamond segments was further improved after magnetized.The alternating magnetic force distributions in the diamond segments were calculated by numerical simulation according to the coupled field theory.In alternating magnetic field,a prodigious swirl current field appeared in the component.The magnetic vibrating due to alternating magnetic force was obvious,which was in favor of microcosmic structure compacter.The numerical analysis results provided direct evidences for that the alternating magnetic treatment can act as an effective technique to improve the microstructure densification of diamond segments.展开更多
Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fract...Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fracturing theories.First,the mathematical model was established,and the seepage governing equation and boundary conditions were obtained.Second,three dimensionless parameters were introduced for simplifying the expressions,and the seepage governing equations were normalized.Third,analytical expressions were derived for the interface opening and liquid pressure.Moreover,the influencing factors of seepage process at the gasketed interface were analyzed.Parametric analyses revealed that,in the normalized criterion of liquid viscosity,the liquid tip coordinate was influenced by the degree of negative pressure in the liquid lag region,which was related to the initial contact stress.The coordinate of the liquid tip affected the liquid pressure distribution and the interface opening,which were analyzed under different liquid tip coordinate conditions.Finally,under two limit states,comparative analysis showed that the results of the variation trend of the proposed method agree well with those of previous research.Overall,the proposed analytical method provides a novel solution for the design of the waterproof in shield tunnels.展开更多
近日,郑州大学网络空间安全学院在医学图像处理方向取得进展,相关研究成果以题为“PointFormer:Keypoint-Guided Transformer for Simultaneous Nuclei Segmentation and Classification in Multi-Tissue Histology Images”的论文在线...近日,郑州大学网络空间安全学院在医学图像处理方向取得进展,相关研究成果以题为“PointFormer:Keypoint-Guided Transformer for Simultaneous Nuclei Segmentation and Classification in Multi-Tissue Histology Images”的论文在线发表在国际权威期刊《IEEE Transactions on Image Processing》(中科院一区TOP,CCF-A类期刊,IF=10.8)和以题为“SimCMC:A Simple Compact Multiview Contrastive Framework for Self-supervised Early Alzheimer’s Disease Diagnosis”的论文在线发表在国际权威期刊《IEEE Transactions on Instrumentation and Measurement》(中科院二区TOP,IF=5.6)。展开更多
In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-p...In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.展开更多
This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low ...This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low resolution thermal infrared imaging,various optimizations have been carried out to improve the speed and accuracy of thermal infrared 3D reconstruction.Firstly,inspired by Boltzmann's law of thermal radiation,distance is incorporated into the NeRF model for the first time,resulting in a nonlinear propagation of a single ray and a more accurate description of the physical property that infrared radiation intensity decreases with increasing distance.Secondly,in terms of improving inference speed,based on the phenomenon of high and low frequency distribution of foreground and background in infrared images,a multi ray non-uniform light synthesis strategy is proposed to make the model pay more attention to foreground objects in the scene,reduce the distribution of light in the background,and significantly reduce training time without reducing accuracy.In addition,compared to visible light scenes,infrared images only have a single channel,so fewer network parameters are required.Experiments using the same training data and data filtering method showed that,compared to the original NeRF,the improved network achieved an average improvement of 13.8%and 4.62%in PSNR and SSIM,respectively,while an average decreases of 46%in LPIPS.And thanks to the optimization of network layers and data filtering methods,training only takes about 25%of the original method's time to achieve convergence.Finally,for scenes with weak backgrounds,this article improves the inference speed of the model by 4-6 times compared to the original NeRF by limiting the query interval of the model.展开更多
For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchma...For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.展开更多
Accurate segmentation of camouflage objects in aerial imagery is vital for improving the efficiency of UAV-based reconnaissance and rescue missions.However,camouflage object segmentation is increasingly challenging du...Accurate segmentation of camouflage objects in aerial imagery is vital for improving the efficiency of UAV-based reconnaissance and rescue missions.However,camouflage object segmentation is increasingly challenging due to advances in both camouflage materials and biological mimicry.Although multispectral-RGB based technology shows promise,conventional dual-aperture multispectral-RGB imaging systems are constrained by imprecise and time-consuming registration and fusion across different modalities,limiting their performance.Here,we propose the Reconstructed Multispectral-RGB Fusion Network(RMRF-Net),which reconstructs RGB images into multispectral ones,enabling efficient multimodal segmentation using only an RGB camera.Specifically,RMRF-Net employs a divergentsimilarity feature correction strategy to minimize reconstruction errors and includes an efficient boundary-aware decoder to enhance object contours.Notably,we establish the first real-world aerial multispectral-RGB semantic segmentation of camouflage objects dataset,including 11 object categories.Experimental results demonstrate that RMRF-Net outperforms existing methods,achieving 17.38 FPS on the NVIDIA Jetson AGX Orin,with only a 0.96%drop in mIoU compared to the RTX 3090,showing its practical applicability in multimodal remote sensing.展开更多
In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken...In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken by stereo vision was presented, After the depth image was obtained, the pixels of each line were scanned and split into straight line segments. The neighbouring relation of line segments was kept in link structure. The groups of three line segments were selected as seed regions. A queue was maintained for storing seed regions, and then the plane region was expanded around the seed region. The process of region growing continued until the queue of seed regions was empty. After trimming, the edges of the planes became smooth. In the end, extracted planes were obtained. In the experiment, two models were used： pipe and stairs. Two planes in pipe mode/and six planes in stairs model were extracted exactly. The speed and precision of algorithm can satisfy the demands of humanoid robot＇s navigation.展开更多
Traditional image segmentation methods based on MRF converge slowly and require pre-defined weight. These disadvantages are addressed, and a fast segmentation approach based on simple Markov random field （MRF） for S...Traditional image segmentation methods based on MRF converge slowly and require pre-defined weight. These disadvantages are addressed, and a fast segmentation approach based on simple Markov random field （MRF） for SAR image is proposed. The approach is firstly used to perform coarse segmentation in blocks. Then the image is modeled with simple MRF and adaptive variable weighting forms are applied in homogeneous and heterogeneous regions. As a result, the convergent speed is accelerated while the segmentation results in homogeneous regions and boarders are improved. Simulations with synthetic and real SAR images demonstrate the effectiveness of the proposed approach.展开更多
Based on the fact that the shear stress along anchorage segment is neither linearly nor uniformly distributed, the load transfer mechanism of the tension type anchor was studied and the mechanical characteristic of an...Based on the fact that the shear stress along anchorage segment is neither linearly nor uniformly distributed, the load transfer mechanism of the tension type anchor was studied and the mechanical characteristic of anchorage segment was analyzed. Shear stress?strain relationship of soil surrounding anchorage body was simplified into three-folding-lines model consisting of elastic phase, elasto-plastic phase and residual phase considering its softening characteristic. Meanwhile, shear displacement method that has been extensively used in the analysis of pile foundation was introduced. Based on elasto-plastic theory, the distributions of displacement, shear stress and axial force along the anchorage segment of tension type anchor were obtained, and the formula for calculating the elastic limit load was also developed accordingly. Finally, an example was given to discuss the variation of stress and displacement in the anchorage segment with the loads exerted on the anchor, and a program was worked out to calculate the anchor maximum bearing capacity. The influence of some parameters on the anchor bearing capacity was discussed, and effective anchorage length was obtained simultaneously. The results show that the shear stress first increases and then decreases and finally trends to the residual strength with increase of distance from bottom of the anchorage body, the displacement increases all the time with the increase of distance from bottom of the anchorage body, and the increase of velocity gradually becomes greater.展开更多
基金Project(50675190) supported by the National Natural Science Foundation of China
文摘The heated test pieces were treated with alternating magnetic field by self-made experimental facility firstly. And influences of magnetic treatment on microstructure densification of Diamond Saw Segments were studied through hardness testing, ultrasonic testing, metallurgical structure and fracture pattern analysis by comparative method. The mechanism of magnetic treatment is analyzed and discussed in the end. The results show that the hardness of test pieces after magnetized are harder than before, that HRB hardness is improved by 3.58 on average. The sound path and amplitude of echo wave both decrease in test pieces after magnetized. The relative pad value of echo wave is regularly related with the microstructure densification, what is profound to further establish the regularity studying the degree of matrices densification using ultrasonic testing. The pores become few and pore shape gradually spheroidizing with the magnetic treatment, and matrices are more homogeneous and compact than the without by metallographic microscope. The degree of matrices densification is further improved after magnetized. The average crystal grain size is finer than the without, and the reason of grain refining is that densification of diamond saw blade improved. Magnetic treatment can act as one kind of effective technique to improve the microstructure densification of diamond saw segments.
基金Projects(51205335,51375411)supported by the National Natural Science Foundation of ChinaProjects(2013J01209,2012J01237)supported by the Natural Science Foundation of Fujian Province,China+2 种基金Project(2014H0049)supported by the Major S&T Program of Fujian Province,ChinaProject(E201400800)supported by the International Cooperation and Exchange Research Plan of Xiamen University of Technology,ChinaProject(YKJ14008R)supported by the Scientific Research for the High Level Talent of Xiamen University of Technology,China
文摘A mathematical model of gear tooth profiles using the ellipse curve, whose curvature is convenient to control by changing the mathematical parameters as its line of action, was built based on the meshing theory. The equation of undercutting condition was derived from the model. A special epicycloidal tooth profile was also presented. An example gear drive with variation of the ellipse parameters was taken to illustrate the proposed method. The contact ratio of the gear drive designed by the proposed method was analyzed. A comparison of the property of the gear drive designed with the involute gear drive was also carried out. The results confirm that the proposed gear drive has higher contact ratio in comparison with the involute gear drive.
基金supported by National Natural Science Foundation of China(50675190)
文摘The heated test pieces of diamond segments were treated by alternating magnetic field,the influences of magnetic treatment on microstructure densification of diamond segments were studied through metallurgical structure analysis.The experiment results indicated that,the densification of diamond segments was further improved after magnetized.The alternating magnetic force distributions in the diamond segments were calculated by numerical simulation according to the coupled field theory.In alternating magnetic field,a prodigious swirl current field appeared in the component.The magnetic vibrating due to alternating magnetic force was obvious,which was in favor of microcosmic structure compacter.The numerical analysis results provided direct evidences for that the alternating magnetic treatment can act as an effective technique to improve the microstructure densification of diamond segments.
基金Project(52278421)supported by the National Natural Science Foundation of ChinaProject(2024ZZTS0754)supported by the Fundamental Research Funds for the Central Universities of Central South University,China+2 种基金Project(2023CXQD067)supported by the Central South University Innovation-Driven Research Programme,ChinaProject(2022QNRC001)supported by Young Elite Scientists Sponsorship Program by CASTProject(2023TJ-N24)supported by the Youth Talent Program by China Railway Society and the Hunan Provincial Science and Technology Promotion Talent Project。
文摘Waterproof performance of gaskets between segments is the focus of shield tunnels.This paper proposed an analytical method for determining seepage characteristics at tunnel-gasketed joints based on the hydraulic fracturing theories.First,the mathematical model was established,and the seepage governing equation and boundary conditions were obtained.Second,three dimensionless parameters were introduced for simplifying the expressions,and the seepage governing equations were normalized.Third,analytical expressions were derived for the interface opening and liquid pressure.Moreover,the influencing factors of seepage process at the gasketed interface were analyzed.Parametric analyses revealed that,in the normalized criterion of liquid viscosity,the liquid tip coordinate was influenced by the degree of negative pressure in the liquid lag region,which was related to the initial contact stress.The coordinate of the liquid tip affected the liquid pressure distribution and the interface opening,which were analyzed under different liquid tip coordinate conditions.Finally,under two limit states,comparative analysis showed that the results of the variation trend of the proposed method agree well with those of previous research.Overall,the proposed analytical method provides a novel solution for the design of the waterproof in shield tunnels.
文摘近日,郑州大学网络空间安全学院在医学图像处理方向取得进展,相关研究成果以题为“PointFormer:Keypoint-Guided Transformer for Simultaneous Nuclei Segmentation and Classification in Multi-Tissue Histology Images”的论文在线发表在国际权威期刊《IEEE Transactions on Image Processing》(中科院一区TOP,CCF-A类期刊,IF=10.8)和以题为“SimCMC:A Simple Compact Multiview Contrastive Framework for Self-supervised Early Alzheimer’s Disease Diagnosis”的论文在线发表在国际权威期刊《IEEE Transactions on Instrumentation and Measurement》(中科院二区TOP,IF=5.6)。
文摘In order to accurately forecast the main engine fuel consumption and reduce the Energy Efficiency Operational Indicator(EEOI)of merchant ships in polar ice areas,the energy transfer relationship between ship-machine-propeller is studied by analyzing the complex force situation during ship navigation and building a MATLAB/Simulink simulation platform based on multi-environmental resistance,propeller efficiency,main engine power,fuel consumption,fuel consumption rate and EEOI calculation module.Considering the environmental factors of wind,wave and ice,the route is divided into sections,the calculation of main engine power,main engine fuel consumption and EEOI for each section is completed,and the speed design is optimized based on the simulation model for each section.Under the requirements of the voyage plan,the optimization results show that the energy efficiency operation index of the whole route is reduced by 3.114%and the fuel consumption is reduced by 9.17 t.
基金Support by the Fundamental Research Funds for the Central Universities(2024300443)the National Natural Science Foundation of China(NSFC)Young Scientists Fund(62405131)。
文摘This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low resolution thermal infrared imaging,various optimizations have been carried out to improve the speed and accuracy of thermal infrared 3D reconstruction.Firstly,inspired by Boltzmann's law of thermal radiation,distance is incorporated into the NeRF model for the first time,resulting in a nonlinear propagation of a single ray and a more accurate description of the physical property that infrared radiation intensity decreases with increasing distance.Secondly,in terms of improving inference speed,based on the phenomenon of high and low frequency distribution of foreground and background in infrared images,a multi ray non-uniform light synthesis strategy is proposed to make the model pay more attention to foreground objects in the scene,reduce the distribution of light in the background,and significantly reduce training time without reducing accuracy.In addition,compared to visible light scenes,infrared images only have a single channel,so fewer network parameters are required.Experiments using the same training data and data filtering method showed that,compared to the original NeRF,the improved network achieved an average improvement of 13.8%and 4.62%in PSNR and SSIM,respectively,while an average decreases of 46%in LPIPS.And thanks to the optimization of network layers and data filtering methods,training only takes about 25%of the original method's time to achieve convergence.Finally,for scenes with weak backgrounds,this article improves the inference speed of the model by 4-6 times compared to the original NeRF by limiting the query interval of the model.
文摘For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.
基金National Natural Science Foundation of China(Grant Nos.62005049 and 62072110)Natural Science Foundation of Fujian Province(Grant No.2020J01451).
文摘Accurate segmentation of camouflage objects in aerial imagery is vital for improving the efficiency of UAV-based reconnaissance and rescue missions.However,camouflage object segmentation is increasingly challenging due to advances in both camouflage materials and biological mimicry.Although multispectral-RGB based technology shows promise,conventional dual-aperture multispectral-RGB imaging systems are constrained by imprecise and time-consuming registration and fusion across different modalities,limiting their performance.Here,we propose the Reconstructed Multispectral-RGB Fusion Network(RMRF-Net),which reconstructs RGB images into multispectral ones,enabling efficient multimodal segmentation using only an RGB camera.Specifically,RMRF-Net employs a divergentsimilarity feature correction strategy to minimize reconstruction errors and includes an efficient boundary-aware decoder to enhance object contours.Notably,we establish the first real-world aerial multispectral-RGB semantic segmentation of camouflage objects dataset,including 11 object categories.Experimental results demonstrate that RMRF-Net outperforms existing methods,achieving 17.38 FPS on the NVIDIA Jetson AGX Orin,with only a 0.96%drop in mIoU compared to the RTX 3090,showing its practical applicability in multimodal remote sensing.
基金Project(60776816) supported by the National Natural Science Foundation of China and Civil Aviation Administration of ChinaProject(8251064101000005) supported by the Natural Science Foundation of Guangdong Province,China
文摘In order to make the humanoid robot walk freely in complicated circumstance, the reliable capabilities for obtaining plane information from its surroundings are demanded. A system for extracting planes from data taken by stereo vision was presented, After the depth image was obtained, the pixels of each line were scanned and split into straight line segments. The neighbouring relation of line segments was kept in link structure. The groups of three line segments were selected as seed regions. A queue was maintained for storing seed regions, and then the plane region was expanded around the seed region. The process of region growing continued until the queue of seed regions was empty. After trimming, the edges of the planes became smooth. In the end, extracted planes were obtained. In the experiment, two models were used： pipe and stairs. Two planes in pipe mode/and six planes in stairs model were extracted exactly. The speed and precision of algorithm can satisfy the demands of humanoid robot＇s navigation.
基金supported by the Specialized Research Found for the Doctoral Program of Higher Education (20070699013)the Natural Science Foundation of Shaanxi Province (2006F05)the Aeronautical Science Foundation (05I53076)
文摘Traditional image segmentation methods based on MRF converge slowly and require pre-defined weight. These disadvantages are addressed, and a fast segmentation approach based on simple Markov random field （MRF） for SAR image is proposed. The approach is firstly used to perform coarse segmentation in blocks. Then the image is modeled with simple MRF and adaptive variable weighting forms are applied in homogeneous and heterogeneous regions. As a result, the convergent speed is accelerated while the segmentation results in homogeneous regions and boarders are improved. Simulations with synthetic and real SAR images demonstrate the effectiveness of the proposed approach.
基金Project(20050532021) supported by the Research Fund for the Doctoral Program of Higher Education
文摘Based on the fact that the shear stress along anchorage segment is neither linearly nor uniformly distributed, the load transfer mechanism of the tension type anchor was studied and the mechanical characteristic of anchorage segment was analyzed. Shear stress?strain relationship of soil surrounding anchorage body was simplified into three-folding-lines model consisting of elastic phase, elasto-plastic phase and residual phase considering its softening characteristic. Meanwhile, shear displacement method that has been extensively used in the analysis of pile foundation was introduced. Based on elasto-plastic theory, the distributions of displacement, shear stress and axial force along the anchorage segment of tension type anchor were obtained, and the formula for calculating the elastic limit load was also developed accordingly. Finally, an example was given to discuss the variation of stress and displacement in the anchorage segment with the loads exerted on the anchor, and a program was worked out to calculate the anchor maximum bearing capacity. The influence of some parameters on the anchor bearing capacity was discussed, and effective anchorage length was obtained simultaneously. The results show that the shear stress first increases and then decreases and finally trends to the residual strength with increase of distance from bottom of the anchorage body, the displacement increases all the time with the increase of distance from bottom of the anchorage body, and the increase of velocity gradually becomes greater.
