The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects...The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects are prone to occur.This leads to an increase in the scrap rate of casings,causing significant resource wastage.Additionally,the presence of cracks poses a significant safety hazard after the casings are put into service.The generation of different types of crack defects in stainless steel casings is closely related to casting stress and the high-temperature concession of the sand mold.Therefore,the types and causes of cracks in stainless steel casing products,based on their structural characteristics,were systematically analyzed.Various sand molds with different internal topology designs were printed using the 3DP technology to investigate the impact of sand mold structures on high-temperature concession.The optimal sand mold structure was used to cast casings,and the crack suppression effect was verified by analyzing its eddy current testing results.The experimental results indicate that the skeleton structure has an excellent effect on suppressing cracks in the casing.This research holds important theoretical and engineering significance in improving the quality of casing castings and reducing production costs.展开更多
Traditional topology optimization methods often suffer from the“dimension curse”problem,wherein the com-putation time increases exponentially with the degrees of freedom in the background grid.Overcoming this challe...Traditional topology optimization methods often suffer from the“dimension curse”problem,wherein the com-putation time increases exponentially with the degrees of freedom in the background grid.Overcoming this challenge,we introduce a real-time topology optimization approach leveraging Conditional Generative Adversarial Networks with Gradient Penalty(CGAN-GP).This innovative method allows for nearly instantaneous prediction of optimized structures.Given a specific boundary condition,the network can produce a unique optimized structure in a one-to-one manner.The process begins by establishing a dataset using simulation data generated through the Solid Isotropic Material with Penalization(SIMP)method.Subsequently,we design a conditional generative adversarial network and train it to generate optimized structures.To further enhance the quality of the optimized structures produced by CGAN-GP,we incorporate Pix2pixGAN.This augmentation results in sharper topologies,yielding structures with enhanced clarity,de-blurring,and edge smoothing.Our proposed method yields a significant reduction in computational time when compared to traditional topology optimization algorithms,all while maintaining an impressive accuracy rate of up to 85%,as demonstrated through numerical examples.展开更多
This paper takes the fuselage bracket of the quadrotor UAV as the object,combined with the characteristics of less constraints in the 3D printing process,achieves the optimal structure of the UAV body structure design...This paper takes the fuselage bracket of the quadrotor UAV as the object,combined with the characteristics of less constraints in the 3D printing process,achieves the optimal structure of the UAV body structure design form,using the inspire topology optimization analysis,with the optimization goal of maximizing the overall stiffness and the optimized structure was checked for strength and verified by 3D printing prototype.The results show that under the premise of meeting the design strength and stiffness requirements,the mass is reduced by 53.29%compared with the original design.The research shows that the application of topology optimization and 3D printing technology to the structural design of UAVs will achieve significant weight reduction effects,providing a feasible way to realize lightweight,complex and integrated design and manufacturing of components.展开更多
3D reconstruction based on single view aims to reconstruct the entire 3D shape of an object from one perspective.When existing methods reconstruct the mesh surface of complex objects,the surface details are difficult ...3D reconstruction based on single view aims to reconstruct the entire 3D shape of an object from one perspective.When existing methods reconstruct the mesh surface of complex objects,the surface details are difficult to predict and the reconstruction visual effect is poor because the mesh representation is not easily integrated into the deep learning framework;the 3D topology is easily limited by predefined templates and inflexible,and unnecessary mesh self-intersections and connections will be generated when reconstructing complex topology,thus destroying the surface details;the training of the reconstruction network is limited by the large amount of information attached to the mesh vertices,and the training time of the reconstructed network is too long.In this paper,we propose a method for fast mesh reconstruction from single view based on Graph Convolutional Network(GCN)and topology modification.We use GCN to ensure the generation of high-quality mesh surfaces and use topology modification to improve the flexibility of the topology.Meanwhile,a feature fusion method is proposed to make full use of the features of each stage of the image hierarchically.We use 3D open dataset ShapeNet to train our network and add a new weight parameter to speed up the training process.Extensive experiments demonstrate that our method can not only reconstruct object meshes on complex topological surfaces,but also has better qualitative and quantitative results.展开更多
Three-degree of freedom（3-DOF） translational parallel manipulators（TPMs） have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on ...Three-degree of freedom（3-DOF） translational parallel manipulators（TPMs） have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on designers＇ intuition, empirical knowledge, or associative reasoning and the topology synthesis researches of 3-DOF TPMs are still limited. In order to find out the atlas of designs for 3-DOF TPMs, a topology search is presented for enumeration of 3-DOF TPMs whose limbs can be modeled as 5-DOF serial chains. The proposed topology search of 3-DOF TPMs is aimed to overcome the sensitivities of the design solution of a 3-DOF TPM for a LARM leg mechanism in a biped robot. The topology search, which is based on the concept of generation and specialization in graph theory, is reported as a step-by-step procedure with desired specifications, principle and rules of generalization, design requirements and constraints, and algorithm of number synthesis. In order to obtain new feasible designs for a chosen example and to limit the search domain under general considerations, one topological generalized kinematic chain is chosen to be specialized. An atlas of new feasible designs is obtained and analyzed for a specific solution as leg mechanisms. The proposed methodology provides a topology search for 3-DOF TPMs for leg mechanisms, but it can be also expanded for other applications and tasks.展开更多
A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crysta...A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crystal X-ray analyses reveal that it crystallizes in monoclinic,space group P21/c with a=7.616（5）,b=7.584（4）,c=12.314（7）,β=105.595（12）o,V=685.0（7）3,Z=4,C8H14O12Pb2,Mr=716.57,Dc=3.474 g/cm3,μ=24.610 mm-1,F（000）=644,the final R=0.0381 and wR=0.1176 for 1465 observed reflections with I 〉 2σ（I）.The complex presents a 2D-layered structure featuring two different types of rings,and has a （4,36）topology based on Pb and butca4-nodes.In solid state,complex 1 shows photoluminescence with the maximum emission intensity at 468 nm under 286 nm excitation.展开更多
Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A bou...Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples.展开更多
As a matter of fact,most natural structures are complex topology structures with intricate holes or irregular surface morphology.These structures can be used as lightweight infill,porous scaffold,energy absorber or mi...As a matter of fact,most natural structures are complex topology structures with intricate holes or irregular surface morphology.These structures can be used as lightweight infill,porous scaffold,energy absorber or micro-reactor.With the rapid advancement of 3D printing,the complex topology structures can now be efficiently and accurately fabricated by stacking layered materials.The novel manufacturing technology and application background put forward new demands and challenges to the current design methodologies of complex topology structures.In this paper,a brief review on the development of recent complex topology structure design methods was provided;meanwhile,the limitations of existing methods and future work are also discussed in the end.展开更多
Nonvolatile electric-field control of the unique physical characteristics of topological insulators (TIs) is essential forthe fundamental research and development of practical electronic devices. Electrically tunable ...Nonvolatile electric-field control of the unique physical characteristics of topological insulators (TIs) is essential forthe fundamental research and development of practical electronic devices. Electrically tunable transport properties throughgating materials have been extensively investigated. However, the relatively weak and volatile tunability limits its practicalapplications in spintronics. Here, we demonstrate the nonvolatile electric-field control of Bi2Te3 transport properties viaconstructing ferroelectric Rashba architectures, i.e., 2D Bi2Te3/a-In2Se3 ferroelectric field-effect transistors. By switchingthe polarization states of a-In2Se3, the Fermi level, resistance, Fermi wave vector, carrier mobility, carrier density andmagnetoresistance (MR) of the Bi2Te3 film can be effectively modulated. Importantly, a shift of the Fermi level towards aband gap with a surface state occurs as switching to a negative polarization state, the contribution of the surface state to theconductivity then increases, thereby increasing the carrier mobility and electron coherence length significantly, resulting inthe enhanced weak anti-localization (WAL) effect. These results provide a nonvolatile electric-field control method to tunethe electronic properties of TI and can further extend to quantum transport properties.展开更多
A new zinc 1,3,5-benzenetricarboxylate Zn3（BTC）2（DMSO）4（BTC=1,3,5-benzenetricarboxylate） has been solvothermally synthesized in DMSO and structurally determined by X-ray single-crystal diffraction.It crystallize...A new zinc 1,3,5-benzenetricarboxylate Zn3（BTC）2（DMSO）4（BTC=1,3,5-benzenetricarboxylate） has been solvothermally synthesized in DMSO and structurally determined by X-ray single-crystal diffraction.It crystallizes in the monoclinic system,space group P21/c with a=10.0861（11）,b=10.2527（11）,c=16.4013（18）,β=95.478（2）°,V=1688.3（3）3,Z=2,Zn3S4C26H30O16,Mr=922.85,Dc=1.815 g/cm3,F（000）=936,μ=2.434 mm-1,R=0.0319 and wR=0.0755.This compound consists of trimeric zinc clusters and BTC linkers.Alternate connection of these trimeric zinc clusters and BTC linkers results in a three-dimensional（3,6）-connected frame-work with rutile topology.展开更多
In the last issue,two case reports separately present examples of the extremely rare and complex congenital heart diseases that show concordant atrioventricular connections to the L-looped ventricles in the presence o...In the last issue,two case reports separately present examples of the extremely rare and complex congenital heart diseases that show concordant atrioventricular connections to the L-looped ventricles in the presence of situs solitus.Both cases highlight that the relationship between the two ventricles within the ventricular mass is not always harmonious with the given atrioventricular connection.Such disharmony between the connections and relationships requires careful assessment of the three basic facets of cardiac building blocks,namely their morphology,the relationship of their component parts,and their connections with the adjacent segments.3D imaging and printing can now facilitate an otherwise difficult diagnosis in such complex situations.Rotation of either the 3D images or the models permit accurate assessment of the ventricular topologic pattern by creating the right ventricular en-face septal view,thus facilitating placement of the observer’s hands.As we now emphasize,an alternative approach,which might prove more attractive to imagers,is to rotate the ventricular mass to provide the ventricular apical view,thus permitting determination of the ventricular relationship without using the hands.展开更多
Customized 3D-printed structural parts are widely used in surgical robotics.To satisfy the mechanical properties and kinematic functions of these structural parts,a topology optimization technique is adopted to obtain...Customized 3D-printed structural parts are widely used in surgical robotics.To satisfy the mechanical properties and kinematic functions of these structural parts,a topology optimization technique is adopted to obtain the optimal structural layout while meeting the constraints and objectives.However,topology optimization currently faces some practical challenges that must be addressed,such as ensuring that structures do not have significant defects when converted to additive manufacturing models.To address this problem,we designed a 3D hierarchical fully convolutional network(FCN)to predict the precise position of the defective structures.Based on the prediction results,an effective repair strategy is adopted to repair the defective structure.A series of experiments is conducted to demonstrate the effectiveness of our approach.Compared to the 2D fully convolutional network and the rule-based detection method,our approach can accurately capture most defect structures and achieve 89.88%precision and 95.59%recall.Furthermore,we investigate the impact of different ways to increase the receptive field of our model,as well as the trade-off between different defect-repairing strategies.The results of the experiment demonstrate that the hierarchical structure,which increases the receptive field,can substantially improve the defect detection performance.To the best of our knowledge,this paper is the first to investigate 3D defect prediction and repair for topology optimization in conjunction with deep learning algorithms,providing practical tools and new perspectives for the subsequent development of topology optimization techniques.展开更多
In order to solve the dynamic reconstruction and local updating problem of three-dimensional geological solids, topology reasoning is used for three-dimensional geological modeling. This can advance the level of the c...In order to solve the dynamic reconstruction and local updating problem of three-dimensional geological solids, topology reasoning is used for three-dimensional geological modeling. This can advance the level of the corresponding section automation in implementing the 3D geological solid dynamical reconstruction by the construction of and reasoning on topology on the 3D curved surface. This method has been successfully used in the Nanjing city geological modeling and the Zijin gold mine modeling. The results prove that this method adapts to coplanar section and noncoplanar section data, and improves the efficiency of 3D geological modeling.展开更多
One novel cobalt coordination polymer, {[Co（HTCB）（4,4＇btb）]＇HzO}n （1, H3TCB = 1,3,5-tris（4-carboxyphenyl）benzene, 4,4＇-btb = 4,4＇-bis（1,2,4-triazol-3-yl）biphenyl）, has been synthesized and characterized ...One novel cobalt coordination polymer, {[Co（HTCB）（4,4＇btb）]＇HzO}n （1, H3TCB = 1,3,5-tris（4-carboxyphenyl）benzene, 4,4＇-btb = 4,4＇-bis（1,2,4-triazol-3-yl）biphenyl）, has been synthesized and characterized by elemental analysis, IR, powder X-ray diffraction （PXRD）, and thermogravimetric （TG） analyses. X-ray diffraction analysis reveals that complex 1 is a 2D 2-fold interpenetrated {44,62}-sql [Co（HTCB）（4,4＇-btb）] sheet based on the 1D [Co（HTCB）]n chains and 1D [Co（4,4＇-btb）]n chains. The crystal of 1 crystallizes in triclinic, space group P1 with a = 9.529（12）, b = 13.914（16）, c = 14.906（17） A, V= 1903（4） A3, Z = 2, C45H34N6CoO71 Mr= 829.71, Dc = 1.448 g/cm3, F（000） = 858 andμ（MoKa） = 0.514 mm-1. The final R = 0.0655 and wR = 0.1136 for 6603 observed reflections with 1 〉 2a（/） and R = 0.1136 and wR = 0.1747 for all data.展开更多
This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111...This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111） on van der Waals （vdW） and non-vdW substrates, with attention paid to twin suppression and strain. Growth along the [221] direction of Bi2Se3 on InP （001） and GaAs （001） substrates is also discussed.展开更多
Topological insulators are insulating in the bulkbut have metallic surface states. Its unique physicochemicalproperties can find numerous applications in electronics,spintronics, photonics, the energy sciences, and th...Topological insulators are insulating in the bulkbut have metallic surface states. Its unique physicochemicalproperties can find numerous applications in electronics,spintronics, photonics, the energy sciences, and thesignal control of transportation. We report an experimentalapproach to synthesize the high-quality single crystal oftopological insulator Bi2Te3 by using self-flux method. Weobtained the optimal preparation conditions by adjustingthe parameters of heat treatment, and successfully preparedthe single-crystal Bi2Te3 sample. The as-grown sampleshave a surface with bright metallic luster and are soft andfragile. Furthermore, Bi2Te3 has the obvious layer structurefrom SEM results. The data of X-ray diffraction andscanning electron microscope show that Bi2Te3 singlecrystal grows along the c-axis with the order of Te（1）–Bi–Te（2）–Bi–Te（1） and crystallizes in the hexagonal systemwith space group of R/3 m. The q–T curve shows that qdecreases with temperature, showing metallic behaviorover the whole temperature range.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52175352)the Xing Liao Ying Cai Project of Liaoning Province(No.XLYC2008036)the Shenyang Youth Innovation Talent Support Program(No.RC220429)。
文摘The important supporting component in a gas turbine is the casing,which has the characteristics of large size,complex structure,and thin wall.In the context of existing 3DP sand casting processes,casting crack defects are prone to occur.This leads to an increase in the scrap rate of casings,causing significant resource wastage.Additionally,the presence of cracks poses a significant safety hazard after the casings are put into service.The generation of different types of crack defects in stainless steel casings is closely related to casting stress and the high-temperature concession of the sand mold.Therefore,the types and causes of cracks in stainless steel casing products,based on their structural characteristics,were systematically analyzed.Various sand molds with different internal topology designs were printed using the 3DP technology to investigate the impact of sand mold structures on high-temperature concession.The optimal sand mold structure was used to cast casings,and the crack suppression effect was verified by analyzing its eddy current testing results.The experimental results indicate that the skeleton structure has an excellent effect on suppressing cracks in the casing.This research holds important theoretical and engineering significance in improving the quality of casing castings and reducing production costs.
基金supported by the National Key Research and Development Projects (Grant Nos.2021YFB3300601,2021YFB3300603,2021YFB3300604)Fundamental Research Funds for the Central Universities (No.DUT22QN241).
文摘Traditional topology optimization methods often suffer from the“dimension curse”problem,wherein the com-putation time increases exponentially with the degrees of freedom in the background grid.Overcoming this challenge,we introduce a real-time topology optimization approach leveraging Conditional Generative Adversarial Networks with Gradient Penalty(CGAN-GP).This innovative method allows for nearly instantaneous prediction of optimized structures.Given a specific boundary condition,the network can produce a unique optimized structure in a one-to-one manner.The process begins by establishing a dataset using simulation data generated through the Solid Isotropic Material with Penalization(SIMP)method.Subsequently,we design a conditional generative adversarial network and train it to generate optimized structures.To further enhance the quality of the optimized structures produced by CGAN-GP,we incorporate Pix2pixGAN.This augmentation results in sharper topologies,yielding structures with enhanced clarity,de-blurring,and edge smoothing.Our proposed method yields a significant reduction in computational time when compared to traditional topology optimization algorithms,all while maintaining an impressive accuracy rate of up to 85%,as demonstrated through numerical examples.
文摘This paper takes the fuselage bracket of the quadrotor UAV as the object,combined with the characteristics of less constraints in the 3D printing process,achieves the optimal structure of the UAV body structure design form,using the inspire topology optimization analysis,with the optimization goal of maximizing the overall stiffness and the optimized structure was checked for strength and verified by 3D printing prototype.The results show that under the premise of meeting the design strength and stiffness requirements,the mass is reduced by 53.29%compared with the original design.The research shows that the application of topology optimization and 3D printing technology to the structural design of UAVs will achieve significant weight reduction effects,providing a feasible way to realize lightweight,complex and integrated design and manufacturing of components.
基金This work was supported,in part,by the Natural Science Foundation of Jiangsu Province under Grant Numbers BK20201136,BK20191401in part,by the National Nature Science Foundation of China under Grant Numbers 61502240,61502096,61304205,61773219in part,by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)fund.
文摘3D reconstruction based on single view aims to reconstruct the entire 3D shape of an object from one perspective.When existing methods reconstruct the mesh surface of complex objects,the surface details are difficult to predict and the reconstruction visual effect is poor because the mesh representation is not easily integrated into the deep learning framework;the 3D topology is easily limited by predefined templates and inflexible,and unnecessary mesh self-intersections and connections will be generated when reconstructing complex topology,thus destroying the surface details;the training of the reconstruction network is limited by the large amount of information attached to the mesh vertices,and the training time of the reconstructed network is too long.In this paper,we propose a method for fast mesh reconstruction from single view based on Graph Convolutional Network(GCN)and topology modification.We use GCN to ensure the generation of high-quality mesh surfaces and use topology modification to improve the flexibility of the topology.Meanwhile,a feature fusion method is proposed to make full use of the features of each stage of the image hierarchically.We use 3D open dataset ShapeNet to train our network and add a new weight parameter to speed up the training process.Extensive experiments demonstrate that our method can not only reconstruct object meshes on complex topological surfaces,but also has better qualitative and quantitative results.
基金supported by the Chinese Scholarship Council(CSC)for his Ph D study and research at LARM in the University of Cassino and South Latium,Italy,during 2013-2015
文摘Three-degree of freedom（3-DOF） translational parallel manipulators（TPMs） have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on designers＇ intuition, empirical knowledge, or associative reasoning and the topology synthesis researches of 3-DOF TPMs are still limited. In order to find out the atlas of designs for 3-DOF TPMs, a topology search is presented for enumeration of 3-DOF TPMs whose limbs can be modeled as 5-DOF serial chains. The proposed topology search of 3-DOF TPMs is aimed to overcome the sensitivities of the design solution of a 3-DOF TPM for a LARM leg mechanism in a biped robot. The topology search, which is based on the concept of generation and specialization in graph theory, is reported as a step-by-step procedure with desired specifications, principle and rules of generalization, design requirements and constraints, and algorithm of number synthesis. In order to obtain new feasible designs for a chosen example and to limit the search domain under general considerations, one topological generalized kinematic chain is chosen to be specialized. An atlas of new feasible designs is obtained and analyzed for a specific solution as leg mechanisms. The proposed methodology provides a topology search for 3-DOF TPMs for leg mechanisms, but it can be also expanded for other applications and tasks.
基金Supported by the Education Department of Jiangxi Province (No. 2007-125)the Initial Fund for Doctors from Jiangxi Normal University
文摘A lead（II） coordination polymer,{[Pb2（butca）（H2O）2]（H2O）2}n （1）,has been synthe-sized by the hydrothermal reaction of Pb（OH）2 and 1,2,3,4-butanetetracarboxylic acid （H4butca） at 160 °C.Single-crystal X-ray analyses reveal that it crystallizes in monoclinic,space group P21/c with a=7.616（5）,b=7.584（4）,c=12.314（7）,β=105.595（12）o,V=685.0（7）3,Z=4,C8H14O12Pb2,Mr=716.57,Dc=3.474 g/cm3,μ=24.610 mm-1,F（000）=644,the final R=0.0381 and wR=0.1176 for 1465 observed reflections with I 〉 2σ（I）.The complex presents a 2D-layered structure featuring two different types of rings,and has a （4,36）topology based on Pb and butca4-nodes.In solid state,complex 1 shows photoluminescence with the maximum emission intensity at 468 nm under 286 nm excitation.
基金supported by the National Natural Science Foundation of China (90816025, 10721062)National Basic Research Program of China (2006CB601205)Program for New Century Excellent Talents in University of the Ministry of Education of China (NCET-04-0272)
文摘Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples.
基金supported by Science Fund for Creative Research Groups of National Natural Science Foundation of China(No.51521064)the National Nature Science Foundation of China(No.51575483).
文摘As a matter of fact,most natural structures are complex topology structures with intricate holes or irregular surface morphology.These structures can be used as lightweight infill,porous scaffold,energy absorber or micro-reactor.With the rapid advancement of 3D printing,the complex topology structures can now be efficiently and accurately fabricated by stacking layered materials.The novel manufacturing technology and application background put forward new demands and challenges to the current design methodologies of complex topology structures.In this paper,a brief review on the development of recent complex topology structure design methods was provided;meanwhile,the limitations of existing methods and future work are also discussed in the end.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004099 and 11974099)the Zhongyuan Leading Talents,Plan for Leading Talent of Fundamental Research of the Central China in 2020,and the Intelligence Introduction Plan of Henan Province in 2021(Grant No.CXJD2021008).
文摘Nonvolatile electric-field control of the unique physical characteristics of topological insulators (TIs) is essential forthe fundamental research and development of practical electronic devices. Electrically tunable transport properties throughgating materials have been extensively investigated. However, the relatively weak and volatile tunability limits its practicalapplications in spintronics. Here, we demonstrate the nonvolatile electric-field control of Bi2Te3 transport properties viaconstructing ferroelectric Rashba architectures, i.e., 2D Bi2Te3/a-In2Se3 ferroelectric field-effect transistors. By switchingthe polarization states of a-In2Se3, the Fermi level, resistance, Fermi wave vector, carrier mobility, carrier density andmagnetoresistance (MR) of the Bi2Te3 film can be effectively modulated. Importantly, a shift of the Fermi level towards aband gap with a surface state occurs as switching to a negative polarization state, the contribution of the surface state to theconductivity then increases, thereby increasing the carrier mobility and electron coherence length significantly, resulting inthe enhanced weak anti-localization (WAL) effect. These results provide a nonvolatile electric-field control method to tunethe electronic properties of TI and can further extend to quantum transport properties.
基金supported by the National Natural Science Foundation of China (No 20871027)the Program for New Century Excellent Talents in University (NCET-07-0169)
文摘A new zinc 1,3,5-benzenetricarboxylate Zn3（BTC）2（DMSO）4（BTC=1,3,5-benzenetricarboxylate） has been solvothermally synthesized in DMSO and structurally determined by X-ray single-crystal diffraction.It crystallizes in the monoclinic system,space group P21/c with a=10.0861（11）,b=10.2527（11）,c=16.4013（18）,β=95.478（2）°,V=1688.3（3）3,Z=2,Zn3S4C26H30O16,Mr=922.85,Dc=1.815 g/cm3,F（000）=936,μ=2.434 mm-1,R=0.0319 and wR=0.0755.This compound consists of trimeric zinc clusters and BTC linkers.Alternate connection of these trimeric zinc clusters and BTC linkers results in a three-dimensional（3,6）-connected frame-work with rutile topology.
文摘In the last issue,two case reports separately present examples of the extremely rare and complex congenital heart diseases that show concordant atrioventricular connections to the L-looped ventricles in the presence of situs solitus.Both cases highlight that the relationship between the two ventricles within the ventricular mass is not always harmonious with the given atrioventricular connection.Such disharmony between the connections and relationships requires careful assessment of the three basic facets of cardiac building blocks,namely their morphology,the relationship of their component parts,and their connections with the adjacent segments.3D imaging and printing can now facilitate an otherwise difficult diagnosis in such complex situations.Rotation of either the 3D images or the models permit accurate assessment of the ventricular topologic pattern by creating the right ventricular en-face septal view,thus facilitating placement of the observer’s hands.As we now emphasize,an alternative approach,which might prove more attractive to imagers,is to rotate the ventricular mass to provide the ventricular apical view,thus permitting determination of the ventricular relationship without using the hands.
基金supported by the National Natural Science Foundation of China(61973293)the Central Guidance on Local Science and Technology Development Fund of Fujian Province,China(2021L3047 and 2020L3028)+1 种基金the Fujian Provincial Science and Technology Plan Project,China(2021Y0048 and 2021j01388)the Open Project Program of Fujian Key Laboratory of Special Intelligent Equipment Measurement and Control,Fujian Special Equipment Inspection and Research Institute,China(FJIES2023KF02).
文摘Customized 3D-printed structural parts are widely used in surgical robotics.To satisfy the mechanical properties and kinematic functions of these structural parts,a topology optimization technique is adopted to obtain the optimal structural layout while meeting the constraints and objectives.However,topology optimization currently faces some practical challenges that must be addressed,such as ensuring that structures do not have significant defects when converted to additive manufacturing models.To address this problem,we designed a 3D hierarchical fully convolutional network(FCN)to predict the precise position of the defective structures.Based on the prediction results,an effective repair strategy is adopted to repair the defective structure.A series of experiments is conducted to demonstrate the effectiveness of our approach.Compared to the 2D fully convolutional network and the rule-based detection method,our approach can accurately capture most defect structures and achieve 89.88%precision and 95.59%recall.Furthermore,we investigate the impact of different ways to increase the receptive field of our model,as well as the trade-off between different defect-repairing strategies.The results of the experiment demonstrate that the hierarchical structure,which increases the receptive field,can substantially improve the defect detection performance.To the best of our knowledge,this paper is the first to investigate 3D defect prediction and repair for topology optimization in conjunction with deep learning algorithms,providing practical tools and new perspectives for the subsequent development of topology optimization techniques.
基金the Research Foundation for Outstanding Young Teachers, China University of Geosciences.
文摘In order to solve the dynamic reconstruction and local updating problem of three-dimensional geological solids, topology reasoning is used for three-dimensional geological modeling. This can advance the level of the corresponding section automation in implementing the 3D geological solid dynamical reconstruction by the construction of and reasoning on topology on the 3D curved surface. This method has been successfully used in the Nanjing city geological modeling and the Zijin gold mine modeling. The results prove that this method adapts to coplanar section and noncoplanar section data, and improves the efficiency of 3D geological modeling.
基金supported by the National Natural Science Foundation of China(20873150)the Natural Science Foundation of Shandong Province(ZR2010BQ023)
文摘One novel cobalt coordination polymer, {[Co（HTCB）（4,4＇btb）]＇HzO}n （1, H3TCB = 1,3,5-tris（4-carboxyphenyl）benzene, 4,4＇-btb = 4,4＇-bis（1,2,4-triazol-3-yl）biphenyl）, has been synthesized and characterized by elemental analysis, IR, powder X-ray diffraction （PXRD）, and thermogravimetric （TG） analyses. X-ray diffraction analysis reveals that complex 1 is a 2D 2-fold interpenetrated {44,62}-sql [Co（HTCB）（4,4＇-btb）] sheet based on the 1D [Co（HTCB）]n chains and 1D [Co（4,4＇-btb）]n chains. The crystal of 1 crystallizes in triclinic, space group P1 with a = 9.529（12）, b = 13.914（16）, c = 14.906（17） A, V= 1903（4） A3, Z = 2, C45H34N6CoO71 Mr= 829.71, Dc = 1.448 g/cm3, F（000） = 858 andμ（MoKa） = 0.514 mm-1. The final R = 0.0655 and wR = 0.1136 for 6603 observed reflections with 1 〉 2a（/） and R = 0.1136 and wR = 0.1747 for all data.
基金supported by the Research Grant Council (RGC) of Hong Kong Special Administrative Region for its financial support under the General Research Funds (Grant Nos. 706110 and 706111)the SRFDP and RGCERG Joint Research Scheme sponsored by the RGC of Hong Kong and the Ministry of Education of China (M-HKU709/l2)
文摘This paper presents an overview of the growth of Bi2Se3, a prototypical three-dimensional topological insulator, by molecular-beam epitaxy on various substrates. Comparison is made between the growth of Bi2 Se3 （111） on van der Waals （vdW） and non-vdW substrates, with attention paid to twin suppression and strain. Growth along the [221] direction of Bi2Se3 on InP （001） and GaAs （001） substrates is also discussed.
基金supported by the National Magnetic Confinement Fusion Science Program (Grant No. 2011GB112001)the Program of International S&T Cooperation (Grant No. 2013DFA 51050)+3 种基金the National Natural Science Foundation of China (Grant No. 11104224, 11004162, 51271155)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110184120029)the Fundamental Research Funds for the Central Universities (Grant No. 2682013ZT16, SWJTU11ZT31, 2682013CX004, SWJTU11BR063)the Science Foundation of Sichuan Province (Grant No. 2011JY0031, 2011JY0130)
文摘Topological insulators are insulating in the bulkbut have metallic surface states. Its unique physicochemicalproperties can find numerous applications in electronics,spintronics, photonics, the energy sciences, and thesignal control of transportation. We report an experimentalapproach to synthesize the high-quality single crystal oftopological insulator Bi2Te3 by using self-flux method. Weobtained the optimal preparation conditions by adjustingthe parameters of heat treatment, and successfully preparedthe single-crystal Bi2Te3 sample. The as-grown sampleshave a surface with bright metallic luster and are soft andfragile. Furthermore, Bi2Te3 has the obvious layer structurefrom SEM results. The data of X-ray diffraction andscanning electron microscope show that Bi2Te3 singlecrystal grows along the c-axis with the order of Te（1）–Bi–Te（2）–Bi–Te（1） and crystallizes in the hexagonal systemwith space group of R/3 m. The q–T curve shows that qdecreases with temperature, showing metallic behaviorover the whole temperature range.
