Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstructi...Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.展开更多
Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses ...Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses of reconfigurable metamaterials.However,this idea is still in the initial exploration stage and faces many constraints.Here,we propose magic cube metamaterials with features of high transparency,multi-gradient phase distribution,full polarization,and high information,which manifest 47.58% optical transmittance,a 6-order phase distribution,a 77% fractional operating bandwidth,and 65.23 times information entropy of their planar counterparts.The reflection phase corresponding to coplanar lattice of the metamaterials can be dynamically and omni-directionally controlled via altering their spatial distributions through individually addressing each rotatable meta-particle while maintaining the polarization states.The optically transparent design allows for real-time visual interaction and sequence mapping of the reconfigurable metamaterials.As two proof-of-concept meta-devices,an achromatic metalens with an unchanged focal length and a switchable multi-functional beam generator is demonstrated by simulations and experiments in an ultra-wide band(8.0-18.0 GHz).This work provides an effective alternative for designing reconfigurable metamaterials with high information-entropy properties,paving a new route toward advanced equipment such as active signal processors and information encryption/decryption systems.展开更多
Background： The accurate measurement of the femoral anteversion （FA） angle is always a topic of much debate in the orthopedic surgery and radiology research. We aimed to explore a new FA measurement method to acqui...Background： The accurate measurement of the femoral anteversion （FA） angle is always a topic of much debate in the orthopedic surgery and radiology research. We aimed to explore a new FA measurement method to acquire accurate results without radiation damage using piglet model. Methods： A total of thirty piglets were assigned to two groups based on the age. Bilateral femora were imaged with 3.0-T magnetic resonance （MR） and 64-slice computed tomography （CT） examinations on all piglets. FA was measured on MR-three-dimensional （3D） postprocessing software with a four-step method： initial validation of the femoral condylar axis, validation of the condylar plane, validation of the femoral neck axis, and line-plane angle measurement of FA. After MR and CT examinations, all piglets were sacrificed and their degree of FA was measured using their excised, dried femora. MR, CT, and dried-femur measurement results were analyzed statistically; M R and CT measurements were compared for accuracy against each other and against the gold standard dried femur measurement. Results： In both groups, the mean FA value measured by MR was lower than that measured by CT. A statistically significant difference was observed between CT- and dried-femur measurements but not between MR- and dried-femur measurements. A higher correlation （0.783 vs. 0.408） and a higher consistency （0.863 vs. 0.578） with dried-femur measurement results were seen for MR measurements than CT measurements in the 1 -week age group. However, in the 8-week age group, similar correlations （0.707 vs. 0.669） and consistencies （0.864 vs. 0.82 l ） were observed. Conclusions： Noninvasive MR-3D-Cube reconstruction was able to accurately measure FA in piglets. Particularly in the 1-week age group with a larger proportion of cartilaginous structures, the correlation and consistency between MR- and dried-femur measurement results were higher than those between CT- and dried-femur measurements, suggesting that MR may be a new useful examination tool for FA-related diseases in children.展开更多
介绍了非线性动力学系统的 L ogistic映射形成混沌序列的方法 ,提出了一种新的置乱方法 :魔方变换。设计了基于魔方变换的图像加密 /解密算法 ,首先由 L ogistic映射生成得到自然数混沌序列 ,以此序列为参数对图像矩阵进行魔方置乱后得...介绍了非线性动力学系统的 L ogistic映射形成混沌序列的方法 ,提出了一种新的置乱方法 :魔方变换。设计了基于魔方变换的图像加密 /解密算法 ,首先由 L ogistic映射生成得到自然数混沌序列 ,以此序列为参数对图像矩阵进行魔方置乱后得到加密图像 ,逆过程即是解密算法。展开更多
基金National Key Research and Development Program of China,Grant/Award Number:2021YFC2902103National Natural Science Foundation of China,Grant/Award Number:51934001Fundamental Research Funds for the Central Universities,Grant/Award Number:2023JCCXLJ02。
文摘Fracture surface contour study is one of the important requirements for characterization and evaluation of the microstructure of rocks.Based on the improved cube covering method and the 3D contour digital reconstruction model,this study proposes a quantitative microstructure characterization method combining the roughness evaluation index and the 3D fractal dimension to study the change rule of the fracture surface morphology after blasting.This method was applied and validated in the study of the fracture microstructure of the rock after blasting.The results show that the fracture morphology characteristics of the 3D contour digital reconstruction model have good correlation with the changes of the blasting action.The undulation rate of the three-dimensional surface profile of the rock is more prone to dramatic rise and dramatic fall morphology.In terms of tilting trend,the tilting direction also shows gradual disorder,with the tilting angle increasing correspondingly.All the roughness evaluation indexes of the rock fissure surface after blasting show a linear and gradually increasing trend as the distance to the bursting center increases;the difference between the two-dimensional roughness evaluation indexes and the three-dimensional ones of the same micro-area rock samples also becomes increasingly larger,among which the three-dimensional fissure roughness coefficient JRC and the surface roughness ratio Rs display better correlation.Compared with the linear fitting formula of the power function relationship,the three-dimensional fractal dimension of the postblast fissure surface is fitted with the values of JRC and Rs,which renders higher correlation coefficients,and the degree of linear fitting of JRC to the three-dimensional fractal dimension is higher.The fractal characteristics of the blast-affected region form a unity with the three-dimensional roughness evaluation of the fissure surface.
基金supported by the National Key Research and Development Program of China(SQ2022YFB3806200)the Shaanxi Province Innovation Capability Promotion Plan(2023-CX-TD-48)+2 种基金the National Natural Science Foundation of China(62401614,62401617)the China Postdoctoral Science Foundation(2023M734275)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZC20233576)。
文摘Traditionally,magic cube configurations,which have been employed to mechanically execute diverse and unconventional structural transformations,are capable of significantly boosting versatile electromagnetic responses of reconfigurable metamaterials.However,this idea is still in the initial exploration stage and faces many constraints.Here,we propose magic cube metamaterials with features of high transparency,multi-gradient phase distribution,full polarization,and high information,which manifest 47.58% optical transmittance,a 6-order phase distribution,a 77% fractional operating bandwidth,and 65.23 times information entropy of their planar counterparts.The reflection phase corresponding to coplanar lattice of the metamaterials can be dynamically and omni-directionally controlled via altering their spatial distributions through individually addressing each rotatable meta-particle while maintaining the polarization states.The optically transparent design allows for real-time visual interaction and sequence mapping of the reconfigurable metamaterials.As two proof-of-concept meta-devices,an achromatic metalens with an unchanged focal length and a switchable multi-functional beam generator is demonstrated by simulations and experiments in an ultra-wide band(8.0-18.0 GHz).This work provides an effective alternative for designing reconfigurable metamaterials with high information-entropy properties,paving a new route toward advanced equipment such as active signal processors and information encryption/decryption systems.
基金grants from the National Natural Science Foundation of China，Outstanding Scientific Fund of Shengjing Hospital
文摘Background： The accurate measurement of the femoral anteversion （FA） angle is always a topic of much debate in the orthopedic surgery and radiology research. We aimed to explore a new FA measurement method to acquire accurate results without radiation damage using piglet model. Methods： A total of thirty piglets were assigned to two groups based on the age. Bilateral femora were imaged with 3.0-T magnetic resonance （MR） and 64-slice computed tomography （CT） examinations on all piglets. FA was measured on MR-three-dimensional （3D） postprocessing software with a four-step method： initial validation of the femoral condylar axis, validation of the condylar plane, validation of the femoral neck axis, and line-plane angle measurement of FA. After MR and CT examinations, all piglets were sacrificed and their degree of FA was measured using their excised, dried femora. MR, CT, and dried-femur measurement results were analyzed statistically; M R and CT measurements were compared for accuracy against each other and against the gold standard dried femur measurement. Results： In both groups, the mean FA value measured by MR was lower than that measured by CT. A statistically significant difference was observed between CT- and dried-femur measurements but not between MR- and dried-femur measurements. A higher correlation （0.783 vs. 0.408） and a higher consistency （0.863 vs. 0.578） with dried-femur measurement results were seen for MR measurements than CT measurements in the 1 -week age group. However, in the 8-week age group, similar correlations （0.707 vs. 0.669） and consistencies （0.864 vs. 0.82 l ） were observed. Conclusions： Noninvasive MR-3D-Cube reconstruction was able to accurately measure FA in piglets. Particularly in the 1-week age group with a larger proportion of cartilaginous structures, the correlation and consistency between MR- and dried-femur measurement results were higher than those between CT- and dried-femur measurements, suggesting that MR may be a new useful examination tool for FA-related diseases in children.
