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Three-dimensional(3D)parametric measurements of individual gravels in the Gobi region using point cloud technique
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作者 JING Xiangyu HUANG Weiyi KAN Jiangming 《Journal of Arid Land》 SCIE CSCD 2024年第4期500-517,共18页
Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materia... Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi surfaces.It is challenging to describe these processes according to a uniform morphology.Therefore,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3D)size and shape of gravel.Collecting morphology information for Gobi gravels is essential for studying its genesis and sand saltation.To enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3D parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3D parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain size.Leveraging multi-view geometry technology for 3D reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear quality.Additionally,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point clouds.Advanced point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3D parameters of individual gravels.These systematic processes allow precise and detailed characterization of individual gravels.For gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodology for measuring 3D parameters of individual gravels.The proposed workflow yields accurate calculations of relevant parameters for Gobi gravels,providing essential data support for subsequent studies on Gobi environments. 展开更多
关键词 Gobi gravels three-dimensional(3d)parameters point cloud 3d reconstruction Random Sample Consensus(RANSAC)algorithm density-Based Spatial Clustering of Applications with Noise(dBSCAN)
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Challenges and Opportunities in Preserving Key Structural Features of 3D-Printed Metal/Covalent Organic Framework
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作者 Ximeng Liu Dan Zhao John Wang 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第8期362-381,共20页
Metal-organic framework(MOF)and covalent organic framework(COF)are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features,such as large surface area,tunable pore size,and ... Metal-organic framework(MOF)and covalent organic framework(COF)are a huge group of advanced porous materials exhibiting attractive and tunable microstructural features,such as large surface area,tunable pore size,and functional surfaces,which have significant values in various application areas.The emerging 3D printing technology further provides MOF and COFs(M/COFs)with higher designability of their macrostructure and demonstrates large achievements in their performance by shaping them into advanced 3D monoliths.However,the currently available 3D printing M/COFs strategy faces a major challenge of severe destruction of M/COFs’microstructural features,both during and after 3D printing.It is envisioned that preserving the microstructure of M/COFs in the 3D-printed monolith will bring a great improvement to the related applications.In this overview,the 3D-printed M/COFs are categorized into M/COF-mixed monoliths and M/COF-covered monoliths.Their differences in the properties,applications,and current research states are discussed.The up-to-date advancements in paste/scaffold composition and printing/covering methods to preserve the superior M/COF microstructure during 3D printing are further discussed for the two types of 3D-printed M/COF.Throughout the analysis of the current states of 3D-printed M/COFs,the expected future research direction to achieve a highly preserved microstructure in the 3D monolith is proposed. 展开更多
关键词 Metal-organic frameworks Covalent organic frameworks 3d printing Microstructure MONOLITH
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Three-dimensional stability calculation method for high and large composite slopes formed by mining stope and inner dump in adjacent open pits
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作者 Zuchao Liang Dong Wang +4 位作者 Guanghe Li Guangyu Sun Mingyu Yu Dong Xia Chunjian Ding 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第4期507-520,共14页
The 2D limit equilibrium method is widely used for slope stability analysis.However,with the advancement of dump engineering,composite slopes often exhibit significant 3D mechanical effects.Consequently,it is of signi... The 2D limit equilibrium method is widely used for slope stability analysis.However,with the advancement of dump engineering,composite slopes often exhibit significant 3D mechanical effects.Consequently,it is of significant importance to develop an effective 3D stability calculation method for composite slopes to enhance the design and stability control of open-pit slope engineering.Using the composite slope formed by the mining stope and inner dump in Baiyinhua No.1 and No.2 open-pit coal mine as a case study,this research investigates the failure mode of composite slopes and establishes spatial shape equations for the sliding mass.By integrating the shear resistance and sliding force of each row of microstrip columns onto the bottom surface of the strip corresponding to the main sliding surface,a novel 2D equivalent physical and mechanical parameters analysis method for the strips on the main sliding surface of 3D sliding masses is proposed.Subsequently,a comprehensive 3D stability calculation method for composite slopes is developed,and the quantitative relationship between the coordinated development distance and its 3D stability coefficients is examined.The analysis reveals that the failure mode of the composite slope is characterized by cutting-bedding sliding,with the arc serving as the side interface and the weak layer as the bottom interface,while the destabilization mechanism primarily involves shear failure.The spatial form equation of the sliding mass comprises an ellipsoid and weak plane equation.The analysis revealed that when the coordinated development distance is 1500 m,the error rate between the 3D stability calculation result and the 2D stability calculation result of the composite slope is less than 8%,thereby verifying the proposed analytical method of equivalent physical and mechanical parameters and the 3D stability calculation method for composite slopes.Furthermore,the3D stability coefficient of the composite slope exhibits an exponential correlation with the coordinated development distance,with the coefficient gradually decreasing as the coordinated development distance increases.These findings provide a theoretical guideline for designing similar slope shape parameters and conducting stability analysis. 展开更多
关键词 Composite slope destabilization mechanism 3d mechanical effect three-dimensional stability Coordinated development distance
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Phase II Clinical Study of Three-Dimensional Printed Coplanar Template Combined with CT-Guided Percutaneous Core Needle Biopsy of Pulmonary Nodules in Elderly Patients
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作者 Wangti Xie Yu Wu +11 位作者 Xiaoshan Cheng Jianbing Hu Fang Wen Jia Xiao Pan Luo Yuqi Su Xiang Yao Jianlong Fang Grong Dan Xianggan Huang Dunqian Liu Jie Weng 《Journal of Biosciences and Medicines》 2024年第7期325-336,共12页
Background: As the population age structure gradually ages, more and more elderly people were found to have pulmonary nodules during physical examinations. Most elderly people had underlying diseases such as heart, lu... Background: As the population age structure gradually ages, more and more elderly people were found to have pulmonary nodules during physical examinations. Most elderly people had underlying diseases such as heart, lung, brain and blood vessels and cannot tolerate surgery. Computed tomography (CT)-guided percutaneous core needle biopsy (CNB) was the first choice for pathological diagnosis and subsequent targeted drugs, immune drugs or ablation treatment. CT-guided percutaneous CNB requires clinicians with rich CNB experience to ensure high CNB accuracy, but it was easy to cause complications such as pneumothorax and hemorrhage. Three-dimensional (3D) printing coplanar template (PCT) combined with CT-guided percutaneous pulmonary CNB biopsy has been used in clinical practice, but there was no prospective, randomized controlled study. Methods: Elderly patients with lung nodules admitted to the Department of Oncology of our hospital from January 2019 to January 2023 were selected. A total of 225 elderly patients were screened, and 30 patients were included after screening. They were randomly divided into experimental group (Group A: 30 cases) and control group (Group B: 30 cases). Group A was given 3D-PCT combined with CT-guided percutaneous pulmonary CNB biopsy, Group B underwent CT-guided percutaneous pulmonary CNB. The primary outcome measure of this study was the accuracy of diagnostic CNB, and the secondary outcome measures were CNB time, number of CNB needles, number of pathological tissues and complications. Results: The diagnostic accuracy of group A and group B was 96.67% and 76.67%, respectively (P = 0.026). There were statistical differences between group A and group B in average CNB time (P = 0.001), number of CNB (1 vs more than 1, P = 0.029), and pathological tissue obtained by CNB (3 vs 1, P = 0.040). There was no statistical difference in the incidence of pneumothorax and hemorrhage between the two groups (P > 0.05). Conclusions: 3D-PCT combined with CT-guided percutaneous CNB can improve the puncture accuracy of elderly patients, shorten the puncture time, reduce the number of punctures, and increase the amount of puncture pathological tissue, without increasing pneumothorax and hemorrhage complications. We look forward to verifying this in a phase III randomized controlled clinical study. . 展开更多
关键词 Pulmonary Nodules Elderly patients three-dimensional (3d) Printed Coplanar Template (PCT) Core Needle Biopsy (CNB) Computed Tomography (CT)
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SAR regional all-azimuth observation orbit design for target 3D reconstruction
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作者 WANG Yanan ZHOU Chaowei +1 位作者 LIU Aifang MAO Qin 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第3期609-618,共10页
Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, ... Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, e.g. SAR interferometry(InSAR) and SAR tomography(TomoSAR), holographic SAR can retrieve 3D structure by observations in azimuth. This paper focuses on designing a novel type of orbit to achieve SAR regional all-azimuth observation(AAO) for embedded targets detection and holographic 3D reconstruction. The ground tracks of the AAO orbit separate the earth surface into grids. Target in these grids can be accessed with an azimuth angle span of360°, which is similar to the flight path of airborne circular SAR(CSAR). Inspired from the successive coverage orbits of optical sensors, several optimizations are made in the proposed method to ensure favorable grazing angles, the performance of 3D reconstruction, and long-term supervision for SAR sensors. Simulation experiments show the regional AAO can be completed within five hours. In addition, a second AAO of the same area can be duplicated in two days. Finally, an airborne SAR data process result is presented to illustrate the significance of AAO in 3D reconstruction. 展开更多
关键词 synthetic aperture radar(SAR) orbit design all-azimuth observation(AAO) three-dimensional(3d)reconstruction successive coverage
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Shear behavior of intact granite under thermo-mechanical coupling and three-dimensional morphology of shear-formed fractures 被引量:1
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作者 Bing Chen Baotang Shen Haiyang Jiang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第3期523-537,共15页
The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear... The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified. 展开更多
关键词 Thermo-mechanical(TM)coupling Peak shear strength three-dimensional(3d)morphological characterization Failure mode Quadrangular pyramid model
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Three-dimensional mixed convection stagnation-point fow past a vertical surface with second-order slip velocity
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作者 A.V.ROSCA N.C.ROSCA I.POP 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第4期641-652,共12页
This study is concerned with the three-dimensional(3D)stagnation-point for the mixed convection flow past a vertical surface considering the first-order and secondorder velocity slips.To the authors’knowledge,this is... This study is concerned with the three-dimensional(3D)stagnation-point for the mixed convection flow past a vertical surface considering the first-order and secondorder velocity slips.To the authors’knowledge,this is the first study presenting this very interesting analysis.Nonlinear partial differential equations for the flow problem are transformed into nonlinear ordinary differential equations(ODEs)by using appropriate similarity transformation.These ODEs with the corresponding boundary conditions are numerically solved by utilizing the bvp4c solver in MATLAB programming language.The effects of the governing parameters on the non-dimensional velocity profiles,temperature profiles,skin friction coefficients,and the local Nusselt number are presented in detail through a series of graphs and tables.Interestingly,it is reported that the reduced skin friction coefficient decreases for the assisting flow situation and increases for the opposing flow situation.The numerical computations of the present work are compared with those from other research available in specific situations,and an excellent consensus is observed.Another exciting feature for this work is the existence of dual solutions.An important remark is that the dual solutions exist for both assisting and opposing flows.A linear stability analysis is performed showing that one solution is stable and the other solution is not stable.We notice that the mixed convection and velocity slip parameters have strong effects on the flow characteristics.These effects are depicted in graphs and discussed in this paper.The obtained results show that the first-order and second-order slip parameters have a considerable effect on the flow,as well as on the heat transfer characteristics. 展开更多
关键词 three-dimensional(3d)mixed convection flow stagnation point flow first-order slip velocity second-order slip velocity numerical solution stability analysis
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Controlled Assembly of Luminescent Lanthanide‑Organic Frameworks via Post‑Treatment of 3D‑Printed Objects 被引量:3
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作者 Jiahui Huang Peiyi Wu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2021年第1期303-316,共14页
Complex multiscale assemblies of metal-organic frameworks are essential in the construction of largescale optical platforms but often restricted by their bulk nature and conventional techniques.The integration of nano... Complex multiscale assemblies of metal-organic frameworks are essential in the construction of largescale optical platforms but often restricted by their bulk nature and conventional techniques.The integration of nanomaterials and 3D printing technologies allows the fabrication of multiscale functional architectures.Our study reports a unique method of controlled 3D assembly purely relying on the post-printing treatment of printed constructs.By immersing a 3D-printed patterned construct consisting of organic ligand in a solution of lanthanide ions,in situ growth of lanthanide metal-organic frameworks(LnMOFs)can rapidly occur,resulting in macroscopic assemblies and tunable fluorescence properties.This phenomenon,caused by coordination and chelation of lanthanide ions,also renders a sub-millimeter resolution and high shape fidelity.As a proof of concept,a type of 3D assembled LnMOFsbased optical sensing platform has demonstrated the feasibility in response to small molecules such as acetone.It is anticipated that the facile printing and design approach developed in this work can be applied to fabricate bespoke multiscale architectures of functional materials with controlled assembly,bringing a realistic and economic prospect. 展开更多
关键词 3d printing Luminescent lanthanide-organic frameworks Macroscopic assembly In situ growth Optical sensing
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3D Carbon Frameworks for Ultrafast Charge/Discharge Rate Supercapacitors with High Energy‑Power Density 被引量:2
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作者 Changyu Leng Zongbin Zhao +6 位作者 Yinzhou Song Lulu Sun Zhuangjun Fan Yongzhen Yang Xuguang Liu Xuzhen Wang Jieshan Qiu 《Nano-Micro Letters》 SCIE EI CAS CSCD 2021年第1期112-122,共11页
Carbon-based electric double layer capacitors(EDLCs)hold tremendous potentials due to their high-power performance and excellent cycle stability.However,the practical use of EDLCs is limited by the low energy density ... Carbon-based electric double layer capacitors(EDLCs)hold tremendous potentials due to their high-power performance and excellent cycle stability.However,the practical use of EDLCs is limited by the low energy density in aqueous electrolyte and sluggish diffusion kinetics in organic or/and ionic liquids electrolyte.Herein,3D carbon frameworks(3DCFs)constructed by interconnected nanocages(10-20 nm)with an ultrathin wall of ca.2 nm have been fabricated,which possess high specific surface area,hierarchical porosity and good conductive network.After deoxidization,the deoxidized 3DCF(3DCFDO)exhibits a record low IR drop of 0.064 V at 100 A g^−1 and ultrafast charge/discharge rate up to 10 V s^−1.The related device can be charged up to 77.4%of its maximum capacitance in 0.65 s at 100 A g^−1 in 6 M KOH.It has been found that the 3DCF-DO has a great affinity to EMIMBF4,resulting in a high specific capacitance of 174 F g^−1 at 1 A g^−1,and a high energy density of 34 Wh kg^−1 at an ultrahigh power density of 150 kW kg^−1 at 4 V after a fast charge in 1.11 s.This work provides a facile fabrication of novel 3D carbon frameworks for supercapacitors with ultrafast charge/discharge rate and high energy-power density. 展开更多
关键词 3d carbon frameworks NANOCAGES Ultrafast charge/discharge rate High energy-power density SUPERCAPACITORS
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Three-dimensional paper-like graphene framework with highly orientated laminar structure as binder-free supercapacitor electrode 被引量:5
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作者 Yidan Gao Yaoyao Zhang +7 位作者 Yong Zhang Lijing Xie Xiaoming Li Fangyuan Su Xianxian Wei Zhiwei Xu Chengmeng Chen Rong Cai 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第1期49-54,共6页
A free-standing paper-like three-dimensional graphene framework(3DGF) with orientated laminar structure and interconnected macropores, was obtained by the hard template-directed ordered assembly. As the sacrificial ... A free-standing paper-like three-dimensional graphene framework(3DGF) with orientated laminar structure and interconnected macropores, was obtained by the hard template-directed ordered assembly. As the sacrificial templates, polystyrene(PS) latex spheres were assembled with graphene oxide(GO) to build up a sandwich type composite film, followed by heat removal of which with a simultaneous reduction of GO. The 3DGF exhibited high specific surface area of 402.5 m2/g, controllable pores and mechanical flexibility, which was employed as the binder-free supercapacitor electrode and shows high specific gravimetric capacitance of 95 F/g at 0.5 A/g, with enhanced rate capability in 3 electrode KOH system. 展开更多
关键词 3d graphene framework Polystyrene Sacrificial template Supercapacitor
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Atomic Modulation of 3D Conductive Frameworks Boost Performance of MnO2 for Coaxial Fiber‑Shaped Supercapacitors 被引量:1
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作者 Xiaona Wang Zhenyu Zhou +6 位作者 Zhijian Sun Jinho Hah Yagang Yao Kyoung‑Sik Moon Jiangtao Di Qingwen Li Ching‑ping Wong 《Nano-Micro Letters》 SCIE EI CAS CSCD 2021年第1期44-55,共12页
Coaxial fiber-shaped supercapacitors are a promising class of energy storage devices requiring high performance for flexible and miniature electronic devices.Yet,they are still struggling from inferior energy density,... Coaxial fiber-shaped supercapacitors are a promising class of energy storage devices requiring high performance for flexible and miniature electronic devices.Yet,they are still struggling from inferior energy density,which comes from the limited choices in materials and structure used.Here,Zn-doped CuO nanowires were designed as 3D framework for aligned distributing high mass loading of MnO2 nanosheets.Zn could be introduced into the CuO crystal lattice to tune the covalency character and thus improve charge transport.The Zn–CuO@MnO2 as positive electrode obtained superior performance without sacrificing its areal and gravimetric capacitances with the increasing of mass loading of MnO2 due to 3D Zn–CuO framework enabling efficient electron transport.A novel category of free-standing asymmetric coaxial fiber-shaped supercapacitor based on Zn0.11CuO@MnO2 core electrode possesses superior specific capacitance and enhanced cell potential window.This asymmetric coaxial structure provides superior performance including higher capacity and better stability under deformation because of sufficient contact between the electrodes and electrolyte.Based on these advantages,the as-prepared asymmetric coaxial fiber-shaped supercapacitor exhibits a high specific capacitance of 296.6 mF cm^−2 and energy density of 133.47μWh cm^−2.In addition,its capacitance retention reaches 76.57%after bending 10,000 times,which demonstrates as-prepared device’s excellent flexibility and long-term cycling stability. 展开更多
关键词 Coaxial fiber-shaped supercapacitors 3d framework Zn-CuO nanowires Zn-CuO@MnO2 core-shell structure
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A COMPUTER CODE FASTOR-3D FOR TRANSIENT THREE-DIMENSIONAL SIMULATION ON FLOW AND HEAT TRANS-FER WITH POROSITY APPROXIMATION
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作者 卢万成 邓保庆 席时桐 《Journal of Shanghai Jiaotong university(Science)》 EI 1997年第2期43-46,52,共5页
ACOMPUTERCODEFASTOR┐3DFORTRANSIENTTHREE┐DIMENSIONALSIMULATIONONFLOWANDHEATTRANS┐FERWITHPOROSITYAPPROXIMATION... ACOMPUTERCODEFASTOR┐3DFORTRANSIENTTHREE┐DIMENSIONALSIMULATIONONFLOWANDHEATTRANS┐FERWITHPOROSITYAPPROXIMATION*LuWancheng(卢万成)D... 展开更多
关键词 three-dimensional SIMULATION FLOW and HEAT transfer POROSITY APPROXIMATION FASTOR3d
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A Three-Dimensional (3D) Environment to Maintain the Integrity of Mouse Testicular Can Cause the Occurrence of Meiosis
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作者 CHU Zhi-li LIU Chao +3 位作者 BAI Yao-fu ZHU Hai-jing HU Yue HUA Jin-lian 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2013年第8期1481-1488,共8页
Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic... Adhesions between different cells and extracellular matrix have been studied extensively in vitro, but little is known about their functions in testicular tissue counterparts. Spermatogonia and their companion somatic cells maintain a close association throughout spermatogenesis and this association is necessary for normal spermatogenesis. In order to keep the relative integrity of the testicular tissues, and to detect the development in vitro, culture testicular tissues in a three- dimensional (3D) agarose matrix was examined. Testicular tissues isolated from 6.5 d postpartum (dpp) mouse were cultured on the top of the matrix for 26 d with a medium height up to 4/5 of the 3D agarose matrix. The results showed that in this 3D culture environment, each type of testicular cells kept the same structure, localization and function as in vivo and might be more biologically relevant to living organisms. After culture, germ cell marker VASA and meiosis markers DAZL and SCP3 showed typical positive analysed by immunofluorescence staining and RT-PCR. It demonstrated that this 3D culture system was able to maintain the number of germ cells and promote the meiosis initiation of male germ cells. 展开更多
关键词 three-dimensional culture 3d MEIOSIS organ culture MOUSE
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Effect of the mineral spatial distribution heterogeneity on the tensile strength of granite:Insights from PFC3D-GBM numerical analysis 被引量:2
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作者 Tao Zhang Liyuan Yu +3 位作者 Yuxuan Peng Hongwen Jing Haijian Su Jiangbo Wei 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第5期1144-1160,共17页
The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow cod... The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow code(PFC),i.e.PFC3D-GBM,is proposed.This model can accomplish the grouping of mineral grains at the 3D scale and then filling them.Then,the effect of the position distribution,geometric size,and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests.The numerical results show that when an external load is applied to a sample,force chains will form around each contact,and the orientation distribution of the force chains is uniform,which is independent of the external load level.Furthermore,the number of high-strength force chains is proportional to the external load level,and the main orientation distribution is consistent with the external loading direction.The main orientation of the cracks is vertical to that of the high-strength force chains.The geometric size of the mineral grains controls the mechanical behaviours.As the average grain size increases,the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases.The number of high-strength force chains increases,leading to an increase in the stress concentration value required for the macroscopic failure of the sample.Due to the highest bonding strength,the generation of transgranular cracks in quartz requires a higher concentrated stress value.With increasing volume composition of quartz,the number of transgranular cracks in quartz distributed in the region connecting both loading points increases,which requires many high-strength force chains.The load level rises,leading to an increase in the tensile strength of the numerical sample. 展开更多
关键词 Rock mechanics Tensile strength Spatial distribution of minerals three-dimensional(3d)grain-based model (GBM) Transgranular contact
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Airborne sparse flight array SAR 3D imaging based on compressed sensing in frequency domain 被引量:1
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作者 TIAN He DONG Chunzhu +1 位作者 YIN Hongcheng YUAN Li 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第1期56-67,共12页
In airborne array synthetic aperture radar(SAR), the three-dimensional(3D) imaging performance and cross-track resolution depends on the length of the equivalent array. In this paper, Barker sequence criterion is used... In airborne array synthetic aperture radar(SAR), the three-dimensional(3D) imaging performance and cross-track resolution depends on the length of the equivalent array. In this paper, Barker sequence criterion is used for sparse flight sampling of airborne array SAR, in order to obtain high cross-track resolution in as few times of flights as possible. Under each flight, the imaging algorithm of back projection(BP) and the data extraction method based on modified uniformly redundant arrays(MURAs) are utilized to obtain complex 3D image pairs. To solve the side-lobe noise in images, the interferometry between each image pair is implemented, and compressed sensing(CS) reconstruction is adopted in the frequency domain. Furthermore, to restore the geometrical relationship between each flight, the phase information corresponding to negative MURA is compensated on each single-pass image reconstructed by CS. Finally,by coherent accumulation of each complex image, the high resolution in cross-track direction is obtained. Simulations and experiments in X-band verify the availability. 展开更多
关键词 three-dimensional(3d)imaging synthetic aperture radar(SAR) sparse flight INTERFEROMETRY compressed sensing(CS)
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Three dimensional porous frameworks for lithium dendrite suppression 被引量:15
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作者 Shuyan Ni Shuangshuang Tan +1 位作者 Qinyou An Liqiang Mai 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2020年第5期73-89,共17页
Lithium metal is a promising anode material owing to its very low electrochemical potential and ultrahigh specific capacity.However,the growth of lithium dendrites could result in a short lifespan,low coulombic effici... Lithium metal is a promising anode material owing to its very low electrochemical potential and ultrahigh specific capacity.However,the growth of lithium dendrites could result in a short lifespan,low coulombic efficiency,and potential safety hazards during the progress of lithium plating/stripping.These factors drastically hinder its application in lithium metal batteries.This review focuses on the use of three dimensional(3D)porous host frameworks to improve Li plating/stripping behaviors,accommodate the change in volume,and suppress or block lithium dendrite growth.Various 3D porous frameworks,including the conductive carbon-based,metal-based,and lithiophilic inorganic-compound frameworks are introduced and summarized in detail.The particular functions,relative developments,and optimized strategies of various 3D porous frameworks for lithium deposition/dissolution behaviors are discussed.Moreover,the challenges and promising developments in the field of Li metal anodes will be discussed at the end of this review. 展开更多
关键词 LITHIUM metal battery 3d porous frameworks LITHIUM dENdRITE LITHIUM SULFUR BATTERIES LITHIUM oxygen BATTERIES Li plating/stripping
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Effects of dry-wet cycles on three-dimensional pore structure and permeability characteristics of granite residual soil using X-ray micro computed tomography 被引量:13
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作者 Ran An Lingwei Kong +1 位作者 Xianwei Zhang Chengsheng Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2022年第3期851-860,共10页
Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive to... Due to seasonal climate alterations,the microstructure and permeability of granite residual soil are easily affected by multiple dry-wet cycles.The X-ray micro computed tomography(micro-CT)acted as a nondestructive tool for characterizing the microstructure of soil samples exposed to a range of damage levels induced by dry-wet cycles.Subsequently,the variations of pore distribution and permeability due to drywet cycling effects were revealed based on three-dimensional(3D)pore distribution analysis and seepage simulations.According to the results,granite residual soils could be separated into four different components,namely,pores,clay,quartz,and hematite,from micro-CT images.The reconstructed 3D pore models dynamically demonstrated the expanding and connecting patterns of pore structures during drywet cycles.The values of porosity and connectivity are positively correlated with the number of dry-wet cycles,which were expressed by exponential and linear functions,respectively.The pore volume probability distribution curves of granite residual soil coincide with the χ^(2)distribution curve,which verifies the effectiveness of the assumption of χ^(2)distribution probability.The pore volume distribution curves suggest that the pores in soils were divided into four types based on their volumes,i.e.micropores,mesopores,macropores,and cracks.From a quantitative and visual perspective,considerable small pores are gradually transformed into cracks with a large volume and a high connectivity.Under the action of dry-wet cycles,the number of seepage flow streamlines which contribute to water permeation in seepage simulation increases distinctly,as well as the permeability and hydraulic conductivity.The calculated hydraulic conductivity is comparable with measured ones with an acceptable error margin in general,verifying the accuracy of seepage simulations based on micro-CT results. 展开更多
关键词 Granite residual soil dry-wet cycle X-ray micro computed tomography(micro-CT) three-dimensional(3d)pore distribution Seepage simulations PERMEABILITY
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Two kinds of contact problems in three-dimensional icosahedral quasicrystals 被引量:8
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作者 Xuefen ZHAO Xing LI Shenghu DING 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第12期1569-1580,共12页
Two kinds of contact problems, i.e., the frictional contact problem and the adhesive contact problem, in three-dimensional (3D) icosahedral quasicrystals are dis- cussed by a complex variable function method. For th... Two kinds of contact problems, i.e., the frictional contact problem and the adhesive contact problem, in three-dimensional (3D) icosahedral quasicrystals are dis- cussed by a complex variable function method. For the frictional contact problem, the contact stress exhibits power singularities at the edge of the contact zone. For the adhe- sive contact problem, the contact stress exhibits oscillatory singularities at the edge of the contact zone. The numerical examples show that for the two kinds of contact problems, the contact stress exhibits singularities, and reaches the maximum value at the edge of the contact zone. The phonon-phason coupling constant has a significant effect on the contact stress intensity, while has little impact on the contact stress distribution regu- lation. The results are consistent with those of the classical elastic materials when the phonon-phason coupling constant is 0. For the adhesive contact problem, the indentation force has positive correlation with the contact displacement, but the phonon-phason cou- pling constant impact is barely perceptible. The validity of the conclusions is verified. 展开更多
关键词 three-dimensional 3d icosahedral quasicrystal Riemann-Hilbert problem contact problem SINGULARITY complex variable function method
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A state-of-the-art review of automated extraction of rock mass discontinuity characteristics using three-dimensional surface models 被引量:5
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作者 Rushikesh Battulwar Masoud Zare-Naghadehi +1 位作者 Ebrahim Emami Javad Sattarvand 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2021年第4期920-936,共17页
In the last two decades,significant research has been conducted in the field of automated extraction of rock mass discontinuity characteristics from three-dimensional(3D)models.This provides several methodologies for ... In the last two decades,significant research has been conducted in the field of automated extraction of rock mass discontinuity characteristics from three-dimensional(3D)models.This provides several methodologies for acquiring discontinuity measurements from 3D models,such as point clouds generated using laser scanning or photogrammetry.However,even with numerous automated and semiautomated methods presented in the literature,there is not one single method that can automatically characterize discontinuities accurately in a minimum of time.In this paper,we critically review all the existing methods proposed in the literature for the extraction of discontinuity characteristics such as joint sets and orientations,persistence,joint spacing,roughness and block size using point clouds,digital elevation maps,or meshes.As a result of this review,we identify the strengths and drawbacks of each method used for extracting those characteristics.We found that the approaches based on voxels and region growing are superior in extracting joint planes from 3D point clouds.Normal tensor voting with trace growth algorithm is a robust method for measuring joint trace length from 3D meshes.Spacing is estimated by calculating the perpendicular distance between joint planes.Several independent roughness indices are presented to quantify roughness from 3D surface models,but there is a need to incorporate these indices into automated methodologies.There is a lack of efficient algorithms for direct computation of block size from 3D rock mass surface models. 展开更多
关键词 Rock mass discontinuity characterization Automatic extraction three-dimensional(3d)point cloud
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Multi-objective strategy to optimize dithering technique for high-quality three-dimensional shape measurement 被引量:2
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作者 蔡宁 陈浙泊 +1 位作者 曹向群 林斌 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第10期381-386,共6页
Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the pro... Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the problem with the latter is that it cannot enhance phase quality directly nor efficiently. In this paper, we present a multi-objective optimization framework for three-dimensional(3D) measurement by utilizing binary defocusing technique. Moreover, a binary patch optimization technique is used to solve the time-consuming issue of genetic algorithm. It is demonstrated that the presented technique consistently obtains significant phase performance improvement under various defocusing amounts. 展开更多
关键词 three-dimensional(3d) SHAPE measurement MULTI-OBJECTIVE dithering GENETIC algorithm
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