DAYU3D is a modern three-dimensional(3D)computer code for thermal-hydraulic design and accident analysis in hightemperature gas-cooled reactors(HTGRs),developed by the Institute of Nuclear and New Energy Technology(IN...DAYU3D is a modern three-dimensional(3D)computer code for thermal-hydraulic design and accident analysis in hightemperature gas-cooled reactors(HTGRs),developed by the Institute of Nuclear and New Energy Technology(INET)at Tsinghua University.Compared to the traditional codes like TINTE,the DAYU3D code has advantages due to its refined framework,improved models,and more efficient algorithms.It is able to simulate the continuous movement of control rods and is more rigorous in treating radiation heat transfer and the break mass flow.Advanced computational methods significantly improve the computational efficiency of DAYU3D,achieving a time reduction of over 60%compared to TINTE.Extensive verification and validation with more than 100 cases demonstrate that DAYU3D is promising for HTGR 3D thermal-hydraulic design and accident analyses.展开更多
This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is e...This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.展开更多
Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this stud...Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.展开更多
Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional imag...Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.展开更多
[Objective] This study aimed to investigate the prevalence and variation of porcine kobuvirus （PKV） in suckling piglets in China. [Method] In 2013-2014, 224 feces samples from suckling piglets with diarrhea in 27 pi...[Objective] This study aimed to investigate the prevalence and variation of porcine kobuvirus （PKV） in suckling piglets in China. [Method] In 2013-2014, 224 feces samples from suckling piglets with diarrhea in 27 pig farms of five provinces in China were collected to detect 3D genes of PKV with RT-PCR method; the sequences and genetic variation of 29 PKV 3D genes were analyzed. [Result] Total positive rate of PKV in feces samples from suckling piglets with diarrhea was 65.18% （146/224）; total positive rate of PKV in pig farms was 85,2% （23/27）; nucleotide sequences and the deduced amino acid sequences of 29 PKV 3D genes shared 87.0%-100% and 92.7%-100% homologies with six PKV-related 3D sequences, respectively. [Conclusion] PKV infection is prevalent in suckling piglets in China; PKV 3D genes exhibit high diversity.展开更多
Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have di...Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.展开更多
With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics s...With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics susceptible to fixed boundaries,which is not conducive to practical applications.Inspired by the motion characteristics of yarn structures,this study investigates a hybrid 3D woven fabric structure that incorporates interlayer warp yarns and normal yarns.Bending stiffness tests,yarn pull-out tests,and ballistic tests are conducted and compared with single-binding yarn structures.Utilizing a validated meso-finite element model,the dynamic deformation and energy absorption mechanisms of the hybrid configuration under impact are elucidated.The results demonstrate that synergistic interactions among various binding yarn structures maintain fabric stability in the absence of boundaries.Normal yarns inhibit horizontal slippage of warp yarns,while multi-layer warp yarns enhance resistance to weft yarn pull-out,thereby facilitating greater yarn participation in direct energy absorption.The hybrid structure exhibited the highest specific energy absorption(SEA)across different boundary conditions,with an average SEA increase of approximately 27%.These insights will facilitate the design of novel hybrid-structured 3D woven fabrics and inform the customization of lightweight protective materials.展开更多
Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulatio...Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulation,low power consumption,and unattended operation,introduce challenges to the design and development of motor drives.We present the design of a permanent magnet synchronous motor suitable for this environment,conducting a quantitative analysis on the impacts of cryogenic conditions on lubricant performance,differential thermal contraction of metallic components,and remanent flux density of neodymium iron boron(N52)permanent magnets.We also implement a labyrinth seal structure,combined with silicone sealing rings,to mitigate ice crystal intrusion risks.Finite element analysis and laboratory tests demonstrate a maximum torque output of 25 Nm.This kind of motor is used in the Antarctic 15 cm Near Infrared Telescope at Dome A,Antarctica.Operation data shows a total encoder feedback error of 0.0678"for the telescope control system with 15"s^(−1)tracking speed at−56.79°C.These results comprehensively validate the high reliability and precision of the motor under the extreme conditions of the polar environment.展开更多
Background:Three-dimensional(3D)printing has revolutionized craniofacial and craniomaxillofacial applications,leading to substantial advancements in patient-specific treatments.In this study,a bibliometric analysis wa...Background:Three-dimensional(3D)printing has revolutionized craniofacial and craniomaxillofacial applications,leading to substantial advancements in patient-specific treatments.In this study,a bibliometric analysis was performed to identify the key contributors,research trends,thematic developments,and collaboration networks in this evolving field.Methods:Two search strategies were employed to ensure a comprehensive analysis:(1)a broad search,in which selected keywords were searched in the title,abstract,and keyword fields to capture all relevant publications,and(2)a title-specific search,in which keywords were restricted to the title field to identify publications with a strong focus on 3D printing in craniofacial and craniomaxillofacial applications.The retrieved dataset was analyzed using VOSviewer and RStudio(bibliometrix package).Results:The broad search retrieved 3534 publications,whereas the title-specific search yielded 280 publications.The analysis of these 280 papers focused on identifying the top authors,universities,and countries,as well as their research dynamics and collaboration networks.A more detailed approach was adopted by examining the titles of these 280 papers.VOSviewer segmented the titles into approximately 800 words,which were then categorized into 18 distinct thematic groups to represent research trends.The focus areas of the ten most cited papers were also analyzed.Conclusion:This bibliometric study provides valuable insights into the progress in 3D printing for craniofacial and craniomaxillofacial applications.By highlighting the key contributors,thematic developments,and collaborative networks,this study offers a foundation for future research in this rapidly advancing field.展开更多
Increasing population in urban areas and limitations of suitable lands for developing houses and urban infrastructure have led to the vertical development in cities.However,these developments are managed by a cadastra...Increasing population in urban areas and limitations of suitable lands for developing houses and urban infrastructure have led to the vertical development in cities.However,these developments are managed by a cadastral system which is mainly two-dimensional and cannot efficiently represent Rights,Restrictions,and Responsibilities(RRRs)in complex scenarios.In fact,a three-dimensional cadastre is required for efficiently registering and representing RRRs.In this paper,a 3D proximity analysis was proposed and implemented to determine RRRs and associated easement rights in non-topology-based data structures.This method can be used to investigate the surrounding spaces of a subject apartment unit or storage in a high-rise.The performance of the developed method was evaluated in a large complex high-rise in Tehran,Iran.The results confirmed that the proposed method can correctly identify the neighbor spaces in complex scenarios.展开更多
Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance.To quantify the mineral dissemination and pore space distribution of an ore particle,a...Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance.To quantify the mineral dissemination and pore space distribution of an ore particle,a cylindrical copper oxide ore sample(I center dot 4.6 mm x 5.6 mm)was scanned using high-resolution X-ray computed tomography(HRXCT),a nondestructive imaging technology,at a spatial resolution of 4.85 mu m.Combined with three-dimensional(3D)image analysis techniques,the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated.In addition,the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques.Furthermore,the pore phase features,including the pore size distribution,pore surface area,pore fractal dimension,pore centerline,and the pore connectivity,were investigated quantitatively.The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated,with a large surface area and low connectivity.This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.展开更多
An elastoplastic method for analyzing the 3D deformation, stress and transverse distribution of tension stress during cold strip rolling is developed. The analysis is based on the elastoplastic variational principle i...An elastoplastic method for analyzing the 3D deformation, stress and transverse distribution of tension stress during cold strip rolling is developed. The analysis is based on the elastoplastic variational principle in which a kinematically admissible velocity field is constructed with the lateral flow function as an unknown function. The stress distribution and volume strain distribution are obtained by solving the simultaneous equations formed by the longitudinal differential equation of equilibrium and constitutive equations. The lateral flow function is determined by minimizing the total energy dissipation rate. Experimental investigation was carried out on a reversible cold mill. The front tension stress distributions in cold rolled strips were measured by a multi roll segmented tension sensing shapemeter. The calculated results are in good agreement with the measured ones.展开更多
An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process ...An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.展开更多
The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plas...The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.展开更多
Little research can be found in relation to the stability of anisotropic and heterogenous soils in three dimensions.In this paper,we propose a study on the three-dimensional(3D)undrained slopes in anisotropic and hete...Little research can be found in relation to the stability of anisotropic and heterogenous soils in three dimensions.In this paper,we propose a study on the three-dimensional(3D)undrained slopes in anisotropic and heterogenous clay using advanced upper and lower bounds finite element limit analysis(FELA).The obtained stability solutions are normalized,and presented by a stability number that is a function of three geometrical ratios and two material ratios,i.e.depth ratio,length ratio,slope angle,shear strength gradient ratio and anisotropic strength ratio.Numerical results are compared with experimental data in the literature,and charts are presented to cover a wide range of design parameters.Using the multivariate adaptive regression splines(MARS)analysis,the respective influence and sensitivity of each design parameter on the stability number and the failure mechanism are investigated.An empirical equation is also developed to effectively estimate the stability number.展开更多
Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis g...Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis greatly reduces the difficulty, and improves the accuracy and efficiency of seismic interpretation and structural analysis. In this paper, we took Qiongxi area in the compressional region of western Sichuan as an example, using two 3D seismic attributes, coherence and instantaneous phase, to identify fault assemblages and variations both vertically and laterally. The results show that the study area mainly consists of NS-, NE- and NEE-trending faults. The NS-trending faults are the largest and have a component of sinistral slip controlling the formation of NEE-trending faults, while the NE-trending faults are intermediate in scale, formed earlier and were cut by the NS-trending faults. Our results demonstrate that using seismic attributes for structural analysis have the following advantages：（1） more details of major fault zones,（2） highlighting minor faults which are hardly traced in seismic migration cube, and（3） easier acquisition of accurate fault systems. The application of seismic attributes provides a new idea for deciphering fine and complicated structures, and will significantly contribute to the development of objective and precise geological interpretation in the future.展开更多
X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. Howe...X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. However, both methods have limitations when diagnosing the whole leg; X-ray imaging does not provide 3D information, and normal CT scanning cannot be performed with a standing posture. Obtaining 3D data regarding the whole leg in a standing posture is clinically important because it enables 3D analysis in the weight bearing condition.Based on these clinical needs, a hardware-based bi-plane X-ray imaging system has been developed; it uses two orthogonal X-ray images. However, such methods have not been made available in general clinics because of the hight cost. Therefore, we proposed a widely adaptive method for 2 D X-ray image and 3D CT scan data. By this method, it is possible to threedimensionally analyze the whole leg in standing posture. The optimal position that generates the most similar image is the captured X-ray image. The algorithm verifies the similarity using the performance of the proposed method by simulation-based experiments. Then, we analyzed the internal-external rotation angle of the femur using real patient data. Approximately 10.55 degrees of internal rotations were found relative to the defined anterior-posterior direction. In this paper, we present a useful registration method using the conventional X-ray image and 3D CT scan data to analyze the whole leg in the weight-bearing condition.展开更多
The transport of fluid, nutrients, and signaling molecules in the bone lacunar-canalicular system （LCS） is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching...The transport of fluid, nutrients, and signaling molecules in the bone lacunar-canalicular system （LCS） is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching （FRAP） approach to quantify load-induced fluid and solute transport in the LCS in situ, but the measurements were limited to cortical regions 30-50 μm underneath the periosteum due to the constrains of laser penetration. With this work, we aimed to expand our understanding of load-induced fluid and solute transport in both trabecular and cortical bone using a multiscaled image-based finite element analysis （FEA） approach. An intact murine tibia was first re-constructed from microCT images into a three-dimensional （3D） linear elastic FEA model, and the matrix deformations at various locations were calculated under axial loading. A segment of the above 3D model was then imported to the biphasic poroelasticity analysis platform （FEBio） to predict load-induced fluid pressure fields, and interstitial solute/fluid flows through LCS in both cortical and trabecular regions. Further, secondary flow effects such as the shear stress and/or drag force acting on osteocytes, the presumed mechano-sensors in bone, were derived using the previously developed ultrastructural model of Brinkman flow in the canaliculi. The material properties assumed in the FEA models were validated against previously obtained strain and FRAP transport data measured on the cortical cortex. Our results demonstrated the feasibility of this computational approach in estimating the fluid flux in the LCS and the cellular stimulation forces （shear and drag forces） for osteocytes in any cortical and trabecular bone locations, allowing further studies of how the activation of osteocytes correlates with in vivo functional bone formation. The study provides a promising platform to reveal potential cellular mechanisms underlying the anabolic power of exercises and physical activities in treating patients with skeletal deficiencies.展开更多
A new method creating depth information for 2D/3D conversion was proposed. The distance between objects is determined by the distances between objects and light source position which is estimated by the analysis of th...A new method creating depth information for 2D/3D conversion was proposed. The distance between objects is determined by the distances between objects and light source position which is estimated by the analysis of the image. The estimated lighting value is used to normalize the image. A threshold value is determined by some weighted operation between the original image and the normalized image. By applying the threshold value to the original image, background area is removed. Depth information of interested area is calculated from the lighting changes. The final 3D images converted with the proposed method are used to verify its effectiveness.展开更多
3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in...3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in case of emergencyhas been an important research area for scientists.Most of the current navigation systems are still in the 2D environmentand that is insufficient to visualize 3D objects and to obtain satisfactory solutions for the 3D environment.Therefore,there is currently still a lack of implementation of 3D network analysis and navigation for indoor spaces in respect toevacuation.The objective of this paper is to investigate and implement 3D visualization and navigation techniques andsolutions for indoor spaces within 3D-GIS.For realizing this,we have proposed a GIS implementation that is capable ofcarrying out 3D visualization of a building model stored in the CityGML format and perform analysis on a networkmodel stored in Oracle Spatial.The proposed GUI also provides routing simulation on the calculated shortest paths withvoice commands and visual instructions.展开更多
文摘DAYU3D is a modern three-dimensional(3D)computer code for thermal-hydraulic design and accident analysis in hightemperature gas-cooled reactors(HTGRs),developed by the Institute of Nuclear and New Energy Technology(INET)at Tsinghua University.Compared to the traditional codes like TINTE,the DAYU3D code has advantages due to its refined framework,improved models,and more efficient algorithms.It is able to simulate the continuous movement of control rods and is more rigorous in treating radiation heat transfer and the break mass flow.Advanced computational methods significantly improve the computational efficiency of DAYU3D,achieving a time reduction of over 60%compared to TINTE.Extensive verification and validation with more than 100 cases demonstrate that DAYU3D is promising for HTGR 3D thermal-hydraulic design and accident analyses.
基金supported by the National Natural Science Foundation of China(Grant Nos.51890912,51979025 and 52011530189).
文摘This article presents a micro-structure tensor enhanced elasto-plastic finite element(FE)method to address strength anisotropy in three-dimensional(3D)soil slope stability analysis.The gravity increase method(GIM)is employed to analyze the stability of 3D anisotropic soil slopes.The accuracy of the proposed method is first verified against the data in the literature.We then simulate the 3D soil slope with a straight slope surface and the convex and concave slope surfaces with a 90turning corner to study the 3D effect on slope stability and the failure mechanism under anisotropy conditions.Based on our numerical results,the end effect significantly impacts the failure mechanism and safety factor.Anisotropy degree notably affects the safety factor,with higher degrees leading to deeper landslides.For concave slopes,they can be approximated by straight slopes with suitable boundary conditions to assess their stability.Furthermore,a case study of the Saint-Alban test embankment A in Quebec,Canada,is provided to demonstrate the applicability of the proposed FE model.
基金financially supported by the National Key R&D Program of China(Grant No.2023YFC3081200)the National Natural Science Foundation of China(Grant Nos.U21A20159 and 52179117).
文摘Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis(3D-DDA)computation.Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing.In this study,aiming at the continuous-discontinuous simulation of 3D-DDA,a highly efficient contact detection strategy is proposed.Firstly,the global direct search(GDS)method is integrated into the 3D-DDA framework to address intricate contact scenarios.Subsequently,all geometric elements,including blocks,faces,edges,and vertices are divided into searchable and unsearchable parts.Contacts between unsearchable geometric elements would be directly inherited,while only searchable geometric elements are involved in contact detection.This strategy significantly reduces the number of geometric elements involved in contact detection,thereby markedly enhancing the computation efficiency.Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method.The rock pillars with different mesh sizes are simulated under self-weight.The deformation and stress are consistent with the analytical results,and the smaller the mesh size,the higher the accuracy.The maximum speedup ratio is 38.46 for this case.Furthermore,the Brazilian splitting test on the discs with different flaws is conducted.The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments,and the maximum speedup ratio is 266.73.Finally,a large-scale impact test is performed,and approximately 3.2 times enhanced efficiency is obtained.The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed,which is more suitable for continuous-discontinuous simulation.
基金Projects(50934002,51074013,51304076,51104100)supported by the National Natural Science Foundation of ChinaProject(IRT0950)supported by the Program for Changjiang Scholars Innovative Research Team in Universities,ChinaProject(2012M510007)supported by China Postdoctoral Science Foundation
文摘Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.
文摘[Objective] This study aimed to investigate the prevalence and variation of porcine kobuvirus （PKV） in suckling piglets in China. [Method] In 2013-2014, 224 feces samples from suckling piglets with diarrhea in 27 pig farms of five provinces in China were collected to detect 3D genes of PKV with RT-PCR method; the sequences and genetic variation of 29 PKV 3D genes were analyzed. [Result] Total positive rate of PKV in feces samples from suckling piglets with diarrhea was 65.18% （146/224）; total positive rate of PKV in pig farms was 85,2% （23/27）; nucleotide sequences and the deduced amino acid sequences of 29 PKV 3D genes shared 87.0%-100% and 92.7%-100% homologies with six PKV-related 3D sequences, respectively. [Conclusion] PKV infection is prevalent in suckling piglets in China; PKV 3D genes exhibit high diversity.
基金financially supported by The Scientific and Technological Research Council of Türkiye(T??B1TAK)with the project number 121C420。
文摘Rockfall hazards pose significant risks to both cultural heritage and populated areas,necessitating comprehensive assessment methodologies.Despite extensive research on rockfalls,only a small number of studies have directly compared empirical methods with modelling approaches.This study investigated rockfalls in five settlements within the Cappadocia region of Türkiye,employing both empirical methods and advanced three-dimensional(3D)probabilistic modeling.The energy line angle approach was applied to identify rockfall propagation zones,while high-resolution digital surface models derived from unmanned aerial vehicle(UAV)imagery facilitated detailed 3D rockfall simulations.Cappadocia’s unique geological setting—comprising alternating layers of ignimbrites and weaker fluviolacustrine deposits—renders it highly susceptible to rockfalls intensified by wetting-drying and freeze-thaw cycles.Results indicate that rockfall propagation characteristics vary markedly between settlements:Göre and Tatlarin exhibit shorter runout distances due to basalt-dominated slopes,whereas Akköy,SoğanlıandŞahinefendi display longer trajectories associated with welded ignimbrites.Empirical cone propagation analyses correspond broadly with field observations,but variations in energy line angles(23°-33°)highlight the necessity for site-specific calibration.Comparative evaluations demonstrate that 3D probabilistic modeling better captures local-scale block dynamics and identifies high-risk areas affected by topographic and structural features such as rockfall ditches.These findings emphasize the importance of integrating empirical and 3D approaches to improve hazard zoning,optimize mitigation structures and guide the protection of Cappadocia’s unique cultural heritage landscape.
基金supports from National Key R&D Program for Young Scientists of China(No.2022YFC3080900)the opening project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ25-25M).
文摘With superior structural integrity and design flexibility,3D woven fabrics exhibit unique potential in ballistic protection applications.However,the anisotropic yarn distribution renders traditional 3D woven fabrics susceptible to fixed boundaries,which is not conducive to practical applications.Inspired by the motion characteristics of yarn structures,this study investigates a hybrid 3D woven fabric structure that incorporates interlayer warp yarns and normal yarns.Bending stiffness tests,yarn pull-out tests,and ballistic tests are conducted and compared with single-binding yarn structures.Utilizing a validated meso-finite element model,the dynamic deformation and energy absorption mechanisms of the hybrid configuration under impact are elucidated.The results demonstrate that synergistic interactions among various binding yarn structures maintain fabric stability in the absence of boundaries.Normal yarns inhibit horizontal slippage of warp yarns,while multi-layer warp yarns enhance resistance to weft yarn pull-out,thereby facilitating greater yarn participation in direct energy absorption.The hybrid structure exhibited the highest specific energy absorption(SEA)across different boundary conditions,with an average SEA increase of approximately 27%.These insights will facilitate the design of novel hybrid-structured 3D woven fabrics and inform the customization of lightweight protective materials.
基金supported by the Space Debris Resear-ch Project,China(KJSP2020010102)the NationalKey R&D Program of China(2022YFC2807300).
文摘Effective motors are crucial for driving astronomical telescopes,especially for those operating in Antarctica,where the harsh environment and operating conditions,including extreme low temperature,ice/snow accumulation,low power consumption,and unattended operation,introduce challenges to the design and development of motor drives.We present the design of a permanent magnet synchronous motor suitable for this environment,conducting a quantitative analysis on the impacts of cryogenic conditions on lubricant performance,differential thermal contraction of metallic components,and remanent flux density of neodymium iron boron(N52)permanent magnets.We also implement a labyrinth seal structure,combined with silicone sealing rings,to mitigate ice crystal intrusion risks.Finite element analysis and laboratory tests demonstrate a maximum torque output of 25 Nm.This kind of motor is used in the Antarctic 15 cm Near Infrared Telescope at Dome A,Antarctica.Operation data shows a total encoder feedback error of 0.0678"for the telescope control system with 15"s^(−1)tracking speed at−56.79°C.These results comprehensively validate the high reliability and precision of the motor under the extreme conditions of the polar environment.
文摘Background:Three-dimensional(3D)printing has revolutionized craniofacial and craniomaxillofacial applications,leading to substantial advancements in patient-specific treatments.In this study,a bibliometric analysis was performed to identify the key contributors,research trends,thematic developments,and collaboration networks in this evolving field.Methods:Two search strategies were employed to ensure a comprehensive analysis:(1)a broad search,in which selected keywords were searched in the title,abstract,and keyword fields to capture all relevant publications,and(2)a title-specific search,in which keywords were restricted to the title field to identify publications with a strong focus on 3D printing in craniofacial and craniomaxillofacial applications.The retrieved dataset was analyzed using VOSviewer and RStudio(bibliometrix package).Results:The broad search retrieved 3534 publications,whereas the title-specific search yielded 280 publications.The analysis of these 280 papers focused on identifying the top authors,universities,and countries,as well as their research dynamics and collaboration networks.A more detailed approach was adopted by examining the titles of these 280 papers.VOSviewer segmented the titles into approximately 800 words,which were then categorized into 18 distinct thematic groups to represent research trends.The focus areas of the ten most cited papers were also analyzed.Conclusion:This bibliometric study provides valuable insights into the progress in 3D printing for craniofacial and craniomaxillofacial applications.By highlighting the key contributors,thematic developments,and collaborative networks,this study offers a foundation for future research in this rapidly advancing field.
文摘Increasing population in urban areas and limitations of suitable lands for developing houses and urban infrastructure have led to the vertical development in cities.However,these developments are managed by a cadastral system which is mainly two-dimensional and cannot efficiently represent Rights,Restrictions,and Responsibilities(RRRs)in complex scenarios.In fact,a three-dimensional cadastre is required for efficiently registering and representing RRRs.In this paper,a 3D proximity analysis was proposed and implemented to determine RRRs and associated easement rights in non-topology-based data structures.This method can be used to investigate the surrounding spaces of a subject apartment unit or storage in a high-rise.The performance of the developed method was evaluated in a large complex high-rise in Tehran,Iran.The results confirmed that the proposed method can correctly identify the neighbor spaces in complex scenarios.
基金financially supported by the National Natural Science Foundation of China(No.51304076)the Natural Science Foundation of Hunan Province,China(No.14JJ4064)
文摘Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance.To quantify the mineral dissemination and pore space distribution of an ore particle,a cylindrical copper oxide ore sample(I center dot 4.6 mm x 5.6 mm)was scanned using high-resolution X-ray computed tomography(HRXCT),a nondestructive imaging technology,at a spatial resolution of 4.85 mu m.Combined with three-dimensional(3D)image analysis techniques,the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated.In addition,the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques.Furthermore,the pore phase features,including the pore size distribution,pore surface area,pore fractal dimension,pore centerline,and the pore connectivity,were investigated quantitatively.The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated,with a large surface area and low connectivity.This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.
基金granted by China Postdoctoral Science Foundation
文摘An elastoplastic method for analyzing the 3D deformation, stress and transverse distribution of tension stress during cold strip rolling is developed. The analysis is based on the elastoplastic variational principle in which a kinematically admissible velocity field is constructed with the lateral flow function as an unknown function. The stress distribution and volume strain distribution are obtained by solving the simultaneous equations formed by the longitudinal differential equation of equilibrium and constitutive equations. The lateral flow function is determined by minimizing the total energy dissipation rate. Experimental investigation was carried out on a reversible cold mill. The front tension stress distributions in cold rolled strips were measured by a multi roll segmented tension sensing shapemeter. The calculated results are in good agreement with the measured ones.
基金Item Sponsored by Youth Science Technology Elitist Foundation of Dalian Local Government (2001-122)
文摘An FE model was developed to study thermal behavior during the rod and wire hot continuous rolling process. The FE code MSC. Marc was used in the simulation using implicit static arithmetic. The whole rolling process of 30 passes was separated and simulated with several continuous 3D elastic-plastic FE models. A rigid pushing body and a data transfer technique were introduced into this model. The on-line experiments were conducted on 304 stainless steel and GCr15 steel hot continuous rolling process to prove the results of simulation by implicit static FEM. The results show that the temperature results of finite element simulations are in good agreement with experiments, which indicate that the FE model developed in this study is effective and efficient.
基金Project(50378036) supported by the National Natural Science Foundation of China
文摘The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate the interaction between pile and soil. The influences of soil depth of layer and number of piles on the lateral pressure of the pile were investigated, and the lateral pressure distributions on the (2×1) pile group and on the (2×2) pile group were compared. The results show that the adjacent surcharge may result in significant lateral movement of the soft soil and considerable pressure on the pile. The pressure acting on the row near the surcharge is higher than that on the other row, due to the "barrier" and arching effects in pile groups. The passive load and its distribution should be taken into account in the design of the passive piles.
文摘Little research can be found in relation to the stability of anisotropic and heterogenous soils in three dimensions.In this paper,we propose a study on the three-dimensional(3D)undrained slopes in anisotropic and heterogenous clay using advanced upper and lower bounds finite element limit analysis(FELA).The obtained stability solutions are normalized,and presented by a stability number that is a function of three geometrical ratios and two material ratios,i.e.depth ratio,length ratio,slope angle,shear strength gradient ratio and anisotropic strength ratio.Numerical results are compared with experimental data in the literature,and charts are presented to cover a wide range of design parameters.Using the multivariate adaptive regression splines(MARS)analysis,the respective influence and sensitivity of each design parameter on the stability number and the failure mechanism are investigated.An empirical equation is also developed to effectively estimate the stability number.
基金supported by the Major National S & T Program (No. 2008ZX050009-001-01)
文摘Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis greatly reduces the difficulty, and improves the accuracy and efficiency of seismic interpretation and structural analysis. In this paper, we took Qiongxi area in the compressional region of western Sichuan as an example, using two 3D seismic attributes, coherence and instantaneous phase, to identify fault assemblages and variations both vertically and laterally. The results show that the study area mainly consists of NS-, NE- and NEE-trending faults. The NS-trending faults are the largest and have a component of sinistral slip controlling the formation of NEE-trending faults, while the NE-trending faults are intermediate in scale, formed earlier and were cut by the NS-trending faults. Our results demonstrate that using seismic attributes for structural analysis have the following advantages：（1） more details of major fault zones,（2） highlighting minor faults which are hardly traced in seismic migration cube, and（3） easier acquisition of accurate fault systems. The application of seismic attributes provides a new idea for deciphering fine and complicated structures, and will significantly contribute to the development of objective and precise geological interpretation in the future.
基金Supported by the KIST institutional program(2E26880,2E26276)
文摘X-ray imaging is the conventional method for diagnosing the orthopedic condition of a patient. Computerized Tomography(CT) scanning is another diagnostic method that provides patient’s 3D anatomical information. However, both methods have limitations when diagnosing the whole leg; X-ray imaging does not provide 3D information, and normal CT scanning cannot be performed with a standing posture. Obtaining 3D data regarding the whole leg in a standing posture is clinically important because it enables 3D analysis in the weight bearing condition.Based on these clinical needs, a hardware-based bi-plane X-ray imaging system has been developed; it uses two orthogonal X-ray images. However, such methods have not been made available in general clinics because of the hight cost. Therefore, we proposed a widely adaptive method for 2 D X-ray image and 3D CT scan data. By this method, it is possible to threedimensionally analyze the whole leg in standing posture. The optimal position that generates the most similar image is the captured X-ray image. The algorithm verifies the similarity using the performance of the proposed method by simulation-based experiments. Then, we analyzed the internal-external rotation angle of the femur using real patient data. Approximately 10.55 degrees of internal rotations were found relative to the defined anterior-posterior direction. In this paper, we present a useful registration method using the conventional X-ray image and 3D CT scan data to analyze the whole leg in the weight-bearing condition.
基金supported by grants from NIH (P30GM103333 and RO1AR054385 to LW)China CSC fellowship (to LF)DOD W81XWH-13-1-0148 (to XLL)
文摘The transport of fluid, nutrients, and signaling molecules in the bone lacunar-canalicular system （LCS） is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching （FRAP） approach to quantify load-induced fluid and solute transport in the LCS in situ, but the measurements were limited to cortical regions 30-50 μm underneath the periosteum due to the constrains of laser penetration. With this work, we aimed to expand our understanding of load-induced fluid and solute transport in both trabecular and cortical bone using a multiscaled image-based finite element analysis （FEA） approach. An intact murine tibia was first re-constructed from microCT images into a three-dimensional （3D） linear elastic FEA model, and the matrix deformations at various locations were calculated under axial loading. A segment of the above 3D model was then imported to the biphasic poroelasticity analysis platform （FEBio） to predict load-induced fluid pressure fields, and interstitial solute/fluid flows through LCS in both cortical and trabecular regions. Further, secondary flow effects such as the shear stress and/or drag force acting on osteocytes, the presumed mechano-sensors in bone, were derived using the previously developed ultrastructural model of Brinkman flow in the canaliculi. The material properties assumed in the FEA models were validated against previously obtained strain and FRAP transport data measured on the cortical cortex. Our results demonstrated the feasibility of this computational approach in estimating the fluid flux in the LCS and the cellular stimulation forces （shear and drag forces） for osteocytes in any cortical and trabecular bone locations, allowing further studies of how the activation of osteocytes correlates with in vivo functional bone formation. The study provides a promising platform to reveal potential cellular mechanisms underlying the anabolic power of exercises and physical activities in treating patients with skeletal deficiencies.
文摘A new method creating depth information for 2D/3D conversion was proposed. The distance between objects is determined by the distances between objects and light source position which is estimated by the analysis of the image. The estimated lighting value is used to normalize the image. A threshold value is determined by some weighted operation between the original image and the normalized image. By applying the threshold value to the original image, background area is removed. Depth information of interested area is calculated from the lighting changes. The final 3D images converted with the proposed method are used to verify its effectiveness.
基金This study was supported by TUBITAK–The Scientific and Technological Research Council of Turkey(Project No.112Y050)research grant.We are indebted for its financial support.
文摘3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in case of emergencyhas been an important research area for scientists.Most of the current navigation systems are still in the 2D environmentand that is insufficient to visualize 3D objects and to obtain satisfactory solutions for the 3D environment.Therefore,there is currently still a lack of implementation of 3D network analysis and navigation for indoor spaces in respect toevacuation.The objective of this paper is to investigate and implement 3D visualization and navigation techniques andsolutions for indoor spaces within 3D-GIS.For realizing this,we have proposed a GIS implementation that is capable ofcarrying out 3D visualization of a building model stored in the CityGML format and perform analysis on a networkmodel stored in Oracle Spatial.The proposed GUI also provides routing simulation on the calculated shortest paths withvoice commands and visual instructions.
