目的探究MR 3D CUBE与常规磁共振成像(MRI)在膝关节前交叉韧带损伤中的应用价值。方法选取2022年1月至2024年4月本院收治的136例膝关节前交叉韧带损伤患者,根据患者损伤程度分为Ⅰ级、Ⅱ级和Ⅲ级;患者均进行MR 3D CUBE与常规MRI检查;Ka...目的探究MR 3D CUBE与常规磁共振成像(MRI)在膝关节前交叉韧带损伤中的应用价值。方法选取2022年1月至2024年4月本院收治的136例膝关节前交叉韧带损伤患者,根据患者损伤程度分为Ⅰ级、Ⅱ级和Ⅲ级;患者均进行MR 3D CUBE与常规MRI检查;Kappa检验分析MR 3D CUBE、常规MRI与关节镜诊断的一致性;以关节镜检查结果为金标准,采用四格表分析MR 3D CUBE与常规MRI对膝关节前交叉韧带不同损伤分级的诊断价值;膝关节前交叉韧带损伤治疗效果的影响因素采用Logistic回归分析。结果MR 3D CUBE、常规MRI与关节镜诊断的一致性较好(Kappa=0.664、0.832,P<0.05)。MR 3D CUBE在诊断膝关节前交叉韧带损伤Ⅰ级时准确度为91.91%,Ⅱ级时准确度为91.18%,Ⅲ级时准确度为94.85%;常规MRI在诊断膝关节前交叉韧带损伤Ⅰ级时准确度为85.29%,Ⅱ级时准确度为83.09%,Ⅲ级时准确度为87.50%,MR 3D CUBE在诊断膝关节前交叉韧带损伤Ⅲ级时准确度显著高于常规MRI(P<0.05)。不良组和良好组病程和既往损伤比较有差异(P<0.05)。多因素Logistic回归分析得知,病程和既往损伤是影响膝关节前交叉韧带损伤患者治疗效果的危险因素(P<0.05)。结论MR 3D CUBE与常规MRI均能诊断膝关节前交叉韧带损伤,但MR 3D CUBE诊断效能高于常规MRI,可在临床应用。展开更多
Infrastructure construction in seasonally frozen regions,covering 23%of total land,faces challenges from freeze-thaw(F-T)induced damages.Expansive soils,as an important problematic soil undergo major hydromechanical p...Infrastructure construction in seasonally frozen regions,covering 23%of total land,faces challenges from freeze-thaw(F-T)induced damages.Expansive soils,as an important problematic soil undergo major hydromechanical properties changes influenced by F-T cycles.Sand-bentonite mixtures are extensively used for constructing earthen hydraulic barriers in cold regions.This study investigates the influence of F-T cycles on multi-directional strains and anisotropic hydraulic conductivity of different sand-bentonite mixtures prepared at optimum water content and experienced three distinct saturation levels.Results indicate that saturation level and bentonite content significantly influence volumetric strain under F-T cycles.The simultaneous effect of ice lens formation,expanding micro-voids,and suction generated by freezing processes cause different volumetric behaviors at varying saturation degrees.The dry specimen exhibits no strain under F-T cycles,while optimum and saturated specimens experienced final volumetric strains of 1.02%and 3.03%,respectively.Notably,during freezing,the specimen at optimumwater content shrank,while the saturated specimen expanded.Increasing bentonite content from 40%to 70%developed freezing-induced shrinkage,from 1.73%to 4.72%,with higher thaw strain attributed to increased specimen plasticity.Also,dimensional variations revealed the cross-anisotropic nature of specimens,highlighting direct influence of water content on the shrinkage ratio.F-T cycles also increased hydraulic conductivity along both orthogonal directions by two orders of magnitude,while the anisotropy ratio decreased by about 3 after 9 F-T cycles,indicating altered pore structures.F-T cycles induce reduced swelling potential and compressibility over subsequent cycles.Microstructural observations also confirmed the F-T effects on the enhancement of porosity.展开更多
The method for optimizing the hydraulic fracturing parameters of the cube development infill well pad was proposed,aiming at the well pattern characteristic of“multi-layer and multi-period”of the infill wells in Sic...The method for optimizing the hydraulic fracturing parameters of the cube development infill well pad was proposed,aiming at the well pattern characteristic of“multi-layer and multi-period”of the infill wells in Sichuan Basin.The fracture propagation and inter-well interference model were established based on the evolution of 4D in-situ stress,and the evolution characteristics of stress and the mechanism of interference between wells were analyzed.The research shows that the increase in horizontal stress difference and the existence of natural fractures/faults are the main reasons for inter-well interference.Inter-well interference is likely to occur near the fracture zones and between the infill wells and parent wells that have been in production for a long time.When communication channels are formed between the infill wells and parent wells,it can increase the productivity of parent wells in the short term.However,it will have a delayed negative impact on the long-term sustained production of both infill wells and parent wells.The change trend of in-situ stress caused by parent well production is basically consistent with the decline trend of pore pressure.The lateral disturbance range of in-situ stress is initially the same as the fracture length and reaches 1.5 to 1.6 times that length after 2.5 years.The key to avoiding inter-well interference is to optimize the fracturing parameters.By adopting the M-shaped well pattern,the optimal well spacing for the infill wells is 300 m,the cluster spacing is 10 m,and the liquid volume per stage is 1800 m^(3).展开更多
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
The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential so...The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.展开更多
The 51st China Beijing International Gifts,Premium and Houseware Exhibition(hereinafter referred to as the Gifts Exhibition) officially opened the kaleidoscope of creative gifts at China International Exhibition Cente...The 51st China Beijing International Gifts,Premium and Houseware Exhibition(hereinafter referred to as the Gifts Exhibition) officially opened the kaleidoscope of creative gifts at China International Exhibition Center (Chaoyang Pavilion) on March 20th.More than 900 exhibitors built an aesthetic corridor of quality life with 200,000 gifts.展开更多
文摘目的探究MR 3D CUBE与常规磁共振成像(MRI)在膝关节前交叉韧带损伤中的应用价值。方法选取2022年1月至2024年4月本院收治的136例膝关节前交叉韧带损伤患者,根据患者损伤程度分为Ⅰ级、Ⅱ级和Ⅲ级;患者均进行MR 3D CUBE与常规MRI检查;Kappa检验分析MR 3D CUBE、常规MRI与关节镜诊断的一致性;以关节镜检查结果为金标准,采用四格表分析MR 3D CUBE与常规MRI对膝关节前交叉韧带不同损伤分级的诊断价值;膝关节前交叉韧带损伤治疗效果的影响因素采用Logistic回归分析。结果MR 3D CUBE、常规MRI与关节镜诊断的一致性较好(Kappa=0.664、0.832,P<0.05)。MR 3D CUBE在诊断膝关节前交叉韧带损伤Ⅰ级时准确度为91.91%,Ⅱ级时准确度为91.18%,Ⅲ级时准确度为94.85%;常规MRI在诊断膝关节前交叉韧带损伤Ⅰ级时准确度为85.29%,Ⅱ级时准确度为83.09%,Ⅲ级时准确度为87.50%,MR 3D CUBE在诊断膝关节前交叉韧带损伤Ⅲ级时准确度显著高于常规MRI(P<0.05)。不良组和良好组病程和既往损伤比较有差异(P<0.05)。多因素Logistic回归分析得知,病程和既往损伤是影响膝关节前交叉韧带损伤患者治疗效果的危险因素(P<0.05)。结论MR 3D CUBE与常规MRI均能诊断膝关节前交叉韧带损伤,但MR 3D CUBE诊断效能高于常规MRI,可在临床应用。
基金The financial support provided by the Research Grant Office at Sharif University Technology(Grant Nos.G4010902 and QB020105)is gratefully acknowledged.
文摘Infrastructure construction in seasonally frozen regions,covering 23%of total land,faces challenges from freeze-thaw(F-T)induced damages.Expansive soils,as an important problematic soil undergo major hydromechanical properties changes influenced by F-T cycles.Sand-bentonite mixtures are extensively used for constructing earthen hydraulic barriers in cold regions.This study investigates the influence of F-T cycles on multi-directional strains and anisotropic hydraulic conductivity of different sand-bentonite mixtures prepared at optimum water content and experienced three distinct saturation levels.Results indicate that saturation level and bentonite content significantly influence volumetric strain under F-T cycles.The simultaneous effect of ice lens formation,expanding micro-voids,and suction generated by freezing processes cause different volumetric behaviors at varying saturation degrees.The dry specimen exhibits no strain under F-T cycles,while optimum and saturated specimens experienced final volumetric strains of 1.02%and 3.03%,respectively.Notably,during freezing,the specimen at optimumwater content shrank,while the saturated specimen expanded.Increasing bentonite content from 40%to 70%developed freezing-induced shrinkage,from 1.73%to 4.72%,with higher thaw strain attributed to increased specimen plasticity.Also,dimensional variations revealed the cross-anisotropic nature of specimens,highlighting direct influence of water content on the shrinkage ratio.F-T cycles also increased hydraulic conductivity along both orthogonal directions by two orders of magnitude,while the anisotropy ratio decreased by about 3 after 9 F-T cycles,indicating altered pore structures.F-T cycles induce reduced swelling potential and compressibility over subsequent cycles.Microstructural observations also confirmed the F-T effects on the enhancement of porosity.
基金Supported by the General Program of the NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA(52374004)National Key Research and Development Program(2023YFF06141022023YFE0110900)。
文摘The method for optimizing the hydraulic fracturing parameters of the cube development infill well pad was proposed,aiming at the well pattern characteristic of“multi-layer and multi-period”of the infill wells in Sichuan Basin.The fracture propagation and inter-well interference model were established based on the evolution of 4D in-situ stress,and the evolution characteristics of stress and the mechanism of interference between wells were analyzed.The research shows that the increase in horizontal stress difference and the existence of natural fractures/faults are the main reasons for inter-well interference.Inter-well interference is likely to occur near the fracture zones and between the infill wells and parent wells that have been in production for a long time.When communication channels are formed between the infill wells and parent wells,it can increase the productivity of parent wells in the short term.However,it will have a delayed negative impact on the long-term sustained production of both infill wells and parent wells.The change trend of in-situ stress caused by parent well production is basically consistent with the decline trend of pore pressure.The lateral disturbance range of in-situ stress is initially the same as the fracture length and reaches 1.5 to 1.6 times that length after 2.5 years.The key to avoiding inter-well interference is to optimize the fracturing parameters.By adopting the M-shaped well pattern,the optimal well spacing for the infill wells is 300 m,the cluster spacing is 10 m,and the liquid volume per stage is 1800 m^(3).
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 Natural Science Foundation of Jiangsu Province(Grant No.BK20240613)Jiangsu Province’s“Innovation and Entrepreneurship Doctor”Program(Grant No.JSSCBS20230088)+4 种基金Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY224123)Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant No.NY222112)Beijing Nova Program(Grant No.20240484696)Wenzhou Major Science and Technology Innovation Key Project(Grant No.ZG2020046)INNOVATION Program for Quantum Science and Technology(Grant No.2021ZD0303200)。
文摘The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.
文摘The 51st China Beijing International Gifts,Premium and Houseware Exhibition(hereinafter referred to as the Gifts Exhibition) officially opened the kaleidoscope of creative gifts at China International Exhibition Center (Chaoyang Pavilion) on March 20th.More than 900 exhibitors built an aesthetic corridor of quality life with 200,000 gifts.
