A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accur...A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accurate composite model at yarn level with material properties ready for use in commercial FE software.The textile representative volume element(RVE)is generated at filament level implementing the digital element method.Yarn structure is determined by filament bundle with variant cross-section shapes along its path.Yarn surface is then extracted using the Delaunay triangulation algorithm and a surface mesh is initiated.Then,the mesh domain is defined and constructed by voxel structure.Periodic boundary conditions,inter-yarn,and yarnmatrix interfaces are eliminated by re-mesh and mesh optimization.An element splitting rule is established to split the voxel unit into sub-elements to create smooth interface.A 3D orthogonal weave fabric reinforced composite is generated and simulated under compressive load.The composite structure and damage morphology are in good agreement with those of the experiment.展开更多
Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles...Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles to meet the demands of high precision and high efficiency in the process of fabricating a curved surface circuit,particularly achieving precise silver circuit molding on irregular substrates.Here,a high-precision and muti-scaled conformal manufacturing method for silver circuits is presented through the digital light processing(DLP)of ultraviolet-curable silver paste(UV-SP)with adjustable photocuring properties,enabling the successful preparation of micro-scaled conductive structure on the sharply skewed hook face.The minimum modeling depth and width of the cured silver paste can be well controlled to 10 and 88µm,respectively.Compared with traditional printing technology,the printing efficiency of complex patterns has increased by over 70%.The printed silver circuit demonstrates an exceptionally high electrical conductivity,reaching as high as 1.16×10^(7) S/m.Additionally,the UV-SP exhibits significant manufacturing efficiency and superior molding resolution compared to conventional direct ink writing and inkjet printing techniques,thereby contributing to the attainment of high precision and efficiency of conformal and micro-molding manufacturing in sensors,communication antennas,and other electronic devices based on curved substrates.展开更多
Ink-jetting printing stands out among various conformal additive manufacturing techniques for its multi-material,digital control,and process flexibility.Ink-jetting-based conformal additive manufacturing is renowned f...Ink-jetting printing stands out among various conformal additive manufacturing techniques for its multi-material,digital control,and process flexibility.Ink-jetting-based conformal additive manufacturing is renowned for its adaptability to complex topological surfaces and is emerging as a critical technology for future comprehensive conformal printing systems.This review highlights the distinctiveness of four primary ink-jetting printing techniques in conformal additive manufacturing—piezoelectric jetting,thermal bubble jetting,aerosol jetting,and electrohydrodynamic jetting—and delves into how these attributes endow ink-jetting printing with unique advantages in conformal processes.Furthermore,leveraging these advantages,the review discusses potential applications in conformal electronics,energy devices,biology,and electromagnetics to bolster the ongoing development and application.Considering the current state of this technology,the review identifies critical challenges for future advancements,such as dynamic surface printing,integrated fabrication of multifunctional conformal structures,and the balance between resolution and throughput.This review summarizes the latest research and technological advancements in ink-jetting-based conformal additive manufacturing,aiding in its innovative applications and enhanced manufacturing capabilities in the future.展开更多
We revisit the issue of whether the effective potential for the conformal factor of the metric,which is generated by quantized matter fields,possesses a non-vanishing vacuum expectation value(VEV)or not.We prove that ...We revisit the issue of whether the effective potential for the conformal factor of the metric,which is generated by quantized matter fields,possesses a non-vanishing vacuum expectation value(VEV)or not.We prove that the effective potential has a vanishing vacuum expectation value on the basis of a global GL(4)symmetry.We also account for why there seems to be two different effective potentials for the conformal factor in a theory,one of which gives rise to a vanishing VEV for the conformal factor,whereas the other has a non-vanishing VEV.展开更多
In this paper,we consider Lie conformal algebras with derivations.A pair consisting of a Lie conformal algebra and a distinguished derivation is called a LieCDer pair.We introduce a cohomology theory for LieCDer pair ...In this paper,we consider Lie conformal algebras with derivations.A pair consisting of a Lie conformal algebra and a distinguished derivation is called a LieCDer pair.We introduce a cohomology theory for LieCDer pair with coefficients in a representation.Furthermore,we study abelian extensions of a LieCDer pair as an application of cohomology theory.Finally,we consider homotopy derivations on 2-term conformal L_(∞)-algebras and 2-derivations on conformal Lie 2-algebras.The category of 2-term conformal L_(∞)-algebras with homotopy derivations is equivalent to the category of conformal Lie 2-algebras with 2-derivations.展开更多
Electromagnetic interference shielding(EMI SE)modules are the core com-ponent of modern electronics.However,the tra-ditional metal-based SE modules always take up indispensable three-dimensional space inside electroni...Electromagnetic interference shielding(EMI SE)modules are the core com-ponent of modern electronics.However,the tra-ditional metal-based SE modules always take up indispensable three-dimensional space inside electronics,posing a major obstacle to the integra-tion of electronics.The innovation of integrating 3D-printed conformal shielding(c-SE)modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE func-tion without occupying additional space.Herein,the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity.Accordingly,the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing.In particular,the SE performance of 3D-printed frame is up to 61.4 dB,simultaneously accompanied with an ultralight architecture of 0.076 g cm^(-3) and a superhigh specific shielding of 802.4 dB cm3 g^(-1).Moreover,as a proof-of-concept,the 3D-printed c-SE module is in situ integrated into core electronics,successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipa-tion.Thus,this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics.展开更多
The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation measures.The literature reports various successful applications of machine learning(ML)models for rockburst asses...The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation measures.The literature reports various successful applications of machine learning(ML)models for rockburst assessment;however,a significant question remains unanswered:How reliable are these models,and at what confidence level are classifications made?Typically,ML models output single rockburst grade even in the face of intricate and out-of-distribution samples,without any associated confidence value.Given the susceptibility of ML models to errors,it becomes imperative to quantify their uncertainty to prevent consequential failures.To address this issue,we propose a conformal prediction(CP)framework built on traditional ML models(extreme gradient boosting and random forest)to generate valid classifications of rockburst while producing a measure of confidence for its output.The proposed framework guarantees marginal coverage and,in most cases,conditional coverage on the test dataset.The CP was evaluated on a rockburst case in the Sanshandao Gold Mine in China,where it achieved high coverage and efficiency at applicable confidence levels.Significantly,the CP identified several“confident”classifications from the traditional ML model as unreliable,necessitating expert verification for informed decision-making.The proposed framework improves the reliability and accuracy of rockburst assessments,with the potential to bolster user confidence.展开更多
The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,a...The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,and added value for aircraft.Through the past decades,remarkable advances have been achieved in manufacturing technologies for conformal windows,where the machining accuracy approaches the nanometer level,and the surface form becomes more complex.These advances are critical to aircraft development,and these manufacturing technologies also have significant reference values for other directions of the ultra-precision machining field.In this review,the infrared materials suitable for manufacturing conformal windows are introduced and compared with insights into their performances.The remarkable advances and concrete work accomplished by researchers are reviewed.The challenges in manufacturing conformal windows that should be faced in the future are discussed.展开更多
Conformal thin-film sensors enable precise monitoring of the operating conditions of components in extreme environments.However,the development of these sensors encounters major challenges,especially in uniformly appl...Conformal thin-film sensors enable precise monitoring of the operating conditions of components in extreme environments.However,the development of these sensors encounters major challenges,especially in uniformly applying multiple film layers on complex metallic surfaces and accurately capturing diverse operational parameters.This work reports a multi-sensor design and multi-layer additive manufacturing process targeting spherical metallic substrates.The proposed high-temperature dip-coating and self-leveling fabrication process achieves high-temperature thin-film coatings with excellent uniformity,high-temperature electrical insulation,and adhesion properties.The fabricated Ag/Pt thin film thermocouple arrays and a heat flux sensor exhibit a maximum temperature resistance of up to 960℃,with thermoelectric potential outputs and hightemperature resistance closely mirroring those of wire-based Ag/Pt thermocouples.Harsh environmental testing was conducted using high-power lasers and a flame gun.The results show that the array of thin-film conformal thermocouples more accurately reflected temperature changes at different points on a spherical surface.The heat flux sensors achieve responses within 95 ms and with-stand environments with heat fluxes over 1.2 MW/m^(2).The proposed multi-sensor design and fabrication method offers promising monitoring applications in harsh environments,including aerospace and nuclear power.展开更多
In this paper,an effective algorithm for optimizing the subarray of conformal arrays is proposed.The method first divides theconformal array into several first-level subarrays.It uses the X algorithm to solve the feas...In this paper,an effective algorithm for optimizing the subarray of conformal arrays is proposed.The method first divides theconformal array into several first-level subarrays.It uses the X algorithm to solve the feasible solution of first-level subarray tiling and employs the particle swarm algorithm to optimize the conformal array subarray tiling scheme with the maximum entropy of the planar mapping as the fitness function.Subsequently,convex optimization is applied to optimize the subarray amplitude phase.Data results verify that the method can effectively find the optimal conformal array tiling scheme.展开更多
Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant chal...Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant challenges for IHB.Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues.This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film(GCF)with mechanical programmability.The regulation of GCF nearly covers soft tissue mechanics,an elastic modulus from 20 to 420 kPa,and a Poisson’s ratio from-0.25 to 0.52.The negative Poisson’s ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces.The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability.Notably,the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration.The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.展开更多
This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole...This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.展开更多
Significant progress has recently been made in enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).The electron transport layer(ETL),as an essential component of PSCs,significantly influences...Significant progress has recently been made in enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).The electron transport layer(ETL),as an essential component of PSCs,significantly influences the performance of devices.Traditional spin-coating method for preparing the ETL fails to fully cover the cusp of FTO transparent conductive glass substrate,leading to direct contact between perovskite film and FTO substrate,which induces charge recombination and reduces the performance of PSCs.To address this issue,an in-situ growth method was proposed to prepare conformal SnO_(2) films on FTO glass substrates in this study.The resulting SnO_(2) films are not only dense and uniform,fully covering the cusp of the FTO glass substrates and reducing the contact area between the FTO substrates and the perovskite films,but also facilitating the formation of perovskite films with large grain sizes.Moreover,the conformal SnO_(2) films can improve the charge extraction at the SnO_(2)/perovskite interface,reduce the trap density and trap-assisted recombination in PSCs,and thus enhance the PCE of PSCs.Through comparative experiments,it is found that the PSCs with in-situ grown SnO_(2) films show an improved PCE of 21.97%,which significantly increased compared to that with spin-coated SnO_(2) films(20.93%).All above data demonstrate that the as-prepared SnO_(2) film can serve as an ideal ETL.It is worth mentioning that this method avoids the use of corrosive hydrochloric acid and toxic thioglycolic acid,and it can also be extended to ITO flexible transparent conductive substrates in the future.展开更多
Using the harmonic map theory,we study the geometry of conformal minimal twospheres immersed in Q_(6),or a real Grassmannian manifold G(2,8;R)equivalently.Then we classify the linearly full reducible conformal minimal...Using the harmonic map theory,we study the geometry of conformal minimal twospheres immersed in Q_(6),or a real Grassmannian manifold G(2,8;R)equivalently.Then we classify the linearly full reducible conformal minimal immersions with constant Gaussian curvature from S^(2)to Q_(6)under some conditions.We also construct specific examples of non-congruent two-spheres with the same Gaussian curvature,up to SO(8)-equivalence,for each case.展开更多
The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced c...The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced cooling performance for plastic products,although they have been underexplored.In this research,CC cavity is designed within the mold geometry,reinforced by body-centered cubic(BCC)lattice structures to enhance mechanical strength.Three distinct BCC lattice variations have been integrated into the CC cavity:the BCC structure,BCC with cubes,and BCC with pillars.The thermal performances of the BCC lattice-added CC cavity are assessed numerically after experimental validation.To provide feasible solutions from viewpoints of thermal performances,various BCC lattice structure thicknesses are analyzed in the range of 0.8–1.2mm.Thermal simulation outcomes reveal that thicker lattice structures enhance mechanical strength but simultaneously lead to an increase in cooling time.Upon examining all the proposed CC cavity solutions supported by BCC,the cooling times range from 2.2 to 4 s,resulting in a reduction of 38.6%to 66.1%when compared to conventional straightdrilled channels.In contrast to CCCs,CC cavities have the potential to decrease the maximum temperature nonuniformity from 8.5 to 6 K.Nevertheless,the presence of lattice structures in CC cavity solutions results in an elevated pressure drop,reaching 2.8MPa,whereas the results for CCCs remain below2.1MPa.展开更多
This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of c...This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.展开更多
Although General Relativity is the classic example of a physical theory based on differential geometry, the momentum tensor is the only part of the field equation that is not derived from or interpreted with different...Although General Relativity is the classic example of a physical theory based on differential geometry, the momentum tensor is the only part of the field equation that is not derived from or interpreted with differential geometry. This work extends General Relativity and Einstein-Cartan theory by augmenting the Poincaré group with projective (special) conformal transformations, which are translations at conformal infinity. Momentum becomes a part of the differential geometry of spacetime. The Lie algebra of these transformations is represented by vectorfields on an associated Minkowski fiber space. Variation of projective conformal scalar curvature generates a 2-index tensor that serves as linear momentum in the field equations of General Relativity. The computation yields a constructive realization of Mach’s principle: local inertia is determined by local motion relative to mass at conformal infinity in each fiber. The vectorfields have a cellular structure that is similar to that of turbulent fluids.展开更多
This paper discusses the feasibility of thin-shell wormholes in spacetimes of embedding class one admitting a one-parameter group of conformal motions. It is shown that the surface energy density σis positive, while ...This paper discusses the feasibility of thin-shell wormholes in spacetimes of embedding class one admitting a one-parameter group of conformal motions. It is shown that the surface energy density σis positive, while the surface pressure is negative, resulting in , thereby signaling a violation of the null energy condition, a necessary condition for holding a wormhole open. For a Morris-Thorne wormhole, matter that violates the null energy condition is referred to as “exotic”. For the thin-shell wormholes in this paper, however, the violation has a physical explanation since it is a direct consequence of the embedding theory in conjunction with the assumption of conformal symmetry. These properties avoid the need to hypothesize the existence of the highly problematical exotic matter.展开更多
基金co-supported by the Chongqing Natural Science Foundation General Project,China(No.CSTB2022NSCQ-MSX1115)。
文摘A structured method to generate conformal finite element(FE)mesh for realistic 3D woven textile reinforced composite is proposed.It is based on a voxel structure mesh reconstruction framework and aims to provide accurate composite model at yarn level with material properties ready for use in commercial FE software.The textile representative volume element(RVE)is generated at filament level implementing the digital element method.Yarn structure is determined by filament bundle with variant cross-section shapes along its path.Yarn surface is then extracted using the Delaunay triangulation algorithm and a surface mesh is initiated.Then,the mesh domain is defined and constructed by voxel structure.Periodic boundary conditions,inter-yarn,and yarnmatrix interfaces are eliminated by re-mesh and mesh optimization.An element splitting rule is established to split the voxel unit into sub-elements to create smooth interface.A 3D orthogonal weave fabric reinforced composite is generated and simulated under compressive load.The composite structure and damage morphology are in good agreement with those of the experiment.
基金supported by the National Natural Science Foundation of China(Nos.51972079 and 52302062)the National Key Research and Development Program of China(Nos.2022YFB370630202 and 2022YFB3706305).
文摘Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles to meet the demands of high precision and high efficiency in the process of fabricating a curved surface circuit,particularly achieving precise silver circuit molding on irregular substrates.Here,a high-precision and muti-scaled conformal manufacturing method for silver circuits is presented through the digital light processing(DLP)of ultraviolet-curable silver paste(UV-SP)with adjustable photocuring properties,enabling the successful preparation of micro-scaled conductive structure on the sharply skewed hook face.The minimum modeling depth and width of the cured silver paste can be well controlled to 10 and 88µm,respectively.Compared with traditional printing technology,the printing efficiency of complex patterns has increased by over 70%.The printed silver circuit demonstrates an exceptionally high electrical conductivity,reaching as high as 1.16×10^(7) S/m.Additionally,the UV-SP exhibits significant manufacturing efficiency and superior molding resolution compared to conventional direct ink writing and inkjet printing techniques,thereby contributing to the attainment of high precision and efficiency of conformal and micro-molding manufacturing in sensors,communication antennas,and other electronic devices based on curved substrates.
基金supported by the National Natural Science Foundation of China(Grant Nos.52005059 and 52375306)the Open Foundation of the Key Laboratory of Advanced Marine Materials(Grant No.2024K01)the Graduate Research and Innovation Foundation of Chongqing,China(Grant No.CYB240011)。
文摘Ink-jetting printing stands out among various conformal additive manufacturing techniques for its multi-material,digital control,and process flexibility.Ink-jetting-based conformal additive manufacturing is renowned for its adaptability to complex topological surfaces and is emerging as a critical technology for future comprehensive conformal printing systems.This review highlights the distinctiveness of four primary ink-jetting printing techniques in conformal additive manufacturing—piezoelectric jetting,thermal bubble jetting,aerosol jetting,and electrohydrodynamic jetting—and delves into how these attributes endow ink-jetting printing with unique advantages in conformal processes.Furthermore,leveraging these advantages,the review discusses potential applications in conformal electronics,energy devices,biology,and electromagnetics to bolster the ongoing development and application.Considering the current state of this technology,the review identifies critical challenges for future advancements,such as dynamic surface printing,integrated fabrication of multifunctional conformal structures,and the balance between resolution and throughput.This review summarizes the latest research and technological advancements in ink-jetting-based conformal additive manufacturing,aiding in its innovative applications and enhanced manufacturing capabilities in the future.
基金supported in part by the JSPS Kakenhi under Grant No.21K03539。
文摘We revisit the issue of whether the effective potential for the conformal factor of the metric,which is generated by quantized matter fields,possesses a non-vanishing vacuum expectation value(VEV)or not.We prove that the effective potential has a vanishing vacuum expectation value on the basis of a global GL(4)symmetry.We also account for why there seems to be two different effective potentials for the conformal factor in a theory,one of which gives rise to a vanishing VEV for the conformal factor,whereas the other has a non-vanishing VEV.
基金Supported by the National Natural Science Foundation of China(Grant No.12161013)the Basic Research Program(Natural Science)of Guizhou Province(Grant No.ZK[2023]025)。
文摘In this paper,we consider Lie conformal algebras with derivations.A pair consisting of a Lie conformal algebra and a distinguished derivation is called a LieCDer pair.We introduce a cohomology theory for LieCDer pair with coefficients in a representation.Furthermore,we study abelian extensions of a LieCDer pair as an application of cohomology theory.Finally,we consider homotopy derivations on 2-term conformal L_(∞)-algebras and 2-derivations on conformal Lie 2-algebras.The category of 2-term conformal L_(∞)-algebras with homotopy derivations is equivalent to the category of conformal Lie 2-algebras with 2-derivations.
基金This work is financially supported by the National Natural Science Foundation of China(52303036)the Natural Science Foundation of Guangxi Province(2020GXNSFAA297028)+4 种基金the Guangxi Science and Technology Base and Talent Special Project(GUIKE AD23026179)the International Science&Technology Cooperation Project of Chengdu(2021-GH03-00009-HZ)the Program of Innovative Research Team for Young Scientists of Sichuan Province(22CXTD0019)the Natural Science Foundation of Sichuan Province(2023NSFSC0986)the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University)(Sklpme2023-3-18).
文摘Electromagnetic interference shielding(EMI SE)modules are the core com-ponent of modern electronics.However,the tra-ditional metal-based SE modules always take up indispensable three-dimensional space inside electronics,posing a major obstacle to the integra-tion of electronics.The innovation of integrating 3D-printed conformal shielding(c-SE)modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE func-tion without occupying additional space.Herein,the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity.Accordingly,the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing.In particular,the SE performance of 3D-printed frame is up to 61.4 dB,simultaneously accompanied with an ultralight architecture of 0.076 g cm^(-3) and a superhigh specific shielding of 802.4 dB cm3 g^(-1).Moreover,as a proof-of-concept,the 3D-printed c-SE module is in situ integrated into core electronics,successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipa-tion.Thus,this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics.
文摘The scientific community recognizes the seriousness of rockbursts and the need for effective mitigation measures.The literature reports various successful applications of machine learning(ML)models for rockburst assessment;however,a significant question remains unanswered:How reliable are these models,and at what confidence level are classifications made?Typically,ML models output single rockburst grade even in the face of intricate and out-of-distribution samples,without any associated confidence value.Given the susceptibility of ML models to errors,it becomes imperative to quantify their uncertainty to prevent consequential failures.To address this issue,we propose a conformal prediction(CP)framework built on traditional ML models(extreme gradient boosting and random forest)to generate valid classifications of rockburst while producing a measure of confidence for its output.The proposed framework guarantees marginal coverage and,in most cases,conditional coverage on the test dataset.The CP was evaluated on a rockburst case in the Sanshandao Gold Mine in China,where it achieved high coverage and efficiency at applicable confidence levels.Significantly,the CP identified several“confident”classifications from the traditional ML model as unreliable,necessitating expert verification for informed decision-making.The proposed framework improves the reliability and accuracy of rockburst assessments,with the potential to bolster user confidence.
基金the support from the National Key Research and Development Program of China[2018YFA0703400].
文摘The infrared conformal window is one of the most critical components in aircraft.Conformal windows with high performance bring low aberrations,high aerodynamic performance,reliability in extreme working environments,and added value for aircraft.Through the past decades,remarkable advances have been achieved in manufacturing technologies for conformal windows,where the machining accuracy approaches the nanometer level,and the surface form becomes more complex.These advances are critical to aircraft development,and these manufacturing technologies also have significant reference values for other directions of the ultra-precision machining field.In this review,the infrared materials suitable for manufacturing conformal windows are introduced and compared with insights into their performances.The remarkable advances and concrete work accomplished by researchers are reviewed.The challenges in manufacturing conformal windows that should be faced in the future are discussed.
基金supported by the National Key Research and Development Program of China(No.2022YFB3203900)。
文摘Conformal thin-film sensors enable precise monitoring of the operating conditions of components in extreme environments.However,the development of these sensors encounters major challenges,especially in uniformly applying multiple film layers on complex metallic surfaces and accurately capturing diverse operational parameters.This work reports a multi-sensor design and multi-layer additive manufacturing process targeting spherical metallic substrates.The proposed high-temperature dip-coating and self-leveling fabrication process achieves high-temperature thin-film coatings with excellent uniformity,high-temperature electrical insulation,and adhesion properties.The fabricated Ag/Pt thin film thermocouple arrays and a heat flux sensor exhibit a maximum temperature resistance of up to 960℃,with thermoelectric potential outputs and hightemperature resistance closely mirroring those of wire-based Ag/Pt thermocouples.Harsh environmental testing was conducted using high-power lasers and a flame gun.The results show that the array of thin-film conformal thermocouples more accurately reflected temperature changes at different points on a spherical surface.The heat flux sensors achieve responses within 95 ms and with-stand environments with heat fluxes over 1.2 MW/m^(2).The proposed multi-sensor design and fabrication method offers promising monitoring applications in harsh environments,including aerospace and nuclear power.
基金supported by the Advanced Functional Composites Technology Key Laboratory Fund under Grant No.6142906220404Sichuan Province Centralized Guided Local Science and Technology Development Special Project under Grant No.2022ZYD0121。
文摘In this paper,an effective algorithm for optimizing the subarray of conformal arrays is proposed.The method first divides theconformal array into several first-level subarrays.It uses the X algorithm to solve the feasible solution of first-level subarray tiling and employs the particle swarm algorithm to optimize the conformal array subarray tiling scheme with the maximum entropy of the planar mapping as the fitness function.Subsequently,convex optimization is applied to optimize the subarray amplitude phase.Data results verify that the method can effectively find the optimal conformal array tiling scheme.
基金This work was sponsored by the National Natural Science Foundation of China(No.52235007,52325504)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.T2121004).
文摘Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant challenges for IHB.Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues.This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film(GCF)with mechanical programmability.The regulation of GCF nearly covers soft tissue mechanics,an elastic modulus from 20 to 420 kPa,and a Poisson’s ratio from-0.25 to 0.52.The negative Poisson’s ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces.The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability.Notably,the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration.The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.
基金DST,New Delhi,India,for its financial support for research facilities under DSTFIST-2019。
文摘This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.
基金Space Application System of China Manned Space Program。
文摘Significant progress has recently been made in enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).The electron transport layer(ETL),as an essential component of PSCs,significantly influences the performance of devices.Traditional spin-coating method for preparing the ETL fails to fully cover the cusp of FTO transparent conductive glass substrate,leading to direct contact between perovskite film and FTO substrate,which induces charge recombination and reduces the performance of PSCs.To address this issue,an in-situ growth method was proposed to prepare conformal SnO_(2) films on FTO glass substrates in this study.The resulting SnO_(2) films are not only dense and uniform,fully covering the cusp of the FTO glass substrates and reducing the contact area between the FTO substrates and the perovskite films,but also facilitating the formation of perovskite films with large grain sizes.Moreover,the conformal SnO_(2) films can improve the charge extraction at the SnO_(2)/perovskite interface,reduce the trap density and trap-assisted recombination in PSCs,and thus enhance the PCE of PSCs.Through comparative experiments,it is found that the PSCs with in-situ grown SnO_(2) films show an improved PCE of 21.97%,which significantly increased compared to that with spin-coated SnO_(2) films(20.93%).All above data demonstrate that the as-prepared SnO_(2) film can serve as an ideal ETL.It is worth mentioning that this method avoids the use of corrosive hydrochloric acid and toxic thioglycolic acid,and it can also be extended to ITO flexible transparent conductive substrates in the future.
基金Supported by the National Natural Science Foundation of China(Grant No.12371055)。
文摘Using the harmonic map theory,we study the geometry of conformal minimal twospheres immersed in Q_(6),or a real Grassmannian manifold G(2,8;R)equivalently.Then we classify the linearly full reducible conformal minimal immersions with constant Gaussian curvature from S^(2)to Q_(6)under some conditions.We also construct specific examples of non-congruent two-spheres with the same Gaussian curvature,up to SO(8)-equivalence,for each case.
文摘The design of three-dimensional printing based conformal cooling channels(CCCs)in injection molding holds great significance.Compared to CCCs,conformal cooling(CC)cavity solutions show promise in delivering enhanced cooling performance for plastic products,although they have been underexplored.In this research,CC cavity is designed within the mold geometry,reinforced by body-centered cubic(BCC)lattice structures to enhance mechanical strength.Three distinct BCC lattice variations have been integrated into the CC cavity:the BCC structure,BCC with cubes,and BCC with pillars.The thermal performances of the BCC lattice-added CC cavity are assessed numerically after experimental validation.To provide feasible solutions from viewpoints of thermal performances,various BCC lattice structure thicknesses are analyzed in the range of 0.8–1.2mm.Thermal simulation outcomes reveal that thicker lattice structures enhance mechanical strength but simultaneously lead to an increase in cooling time.Upon examining all the proposed CC cavity solutions supported by BCC,the cooling times range from 2.2 to 4 s,resulting in a reduction of 38.6%to 66.1%when compared to conventional straightdrilled channels.In contrast to CCCs,CC cavities have the potential to decrease the maximum temperature nonuniformity from 8.5 to 6 K.Nevertheless,the presence of lattice structures in CC cavity solutions results in an elevated pressure drop,reaching 2.8MPa,whereas the results for CCCs remain below2.1MPa.
基金Supported by National Natural Science Foundation of China(Grant Nos.52075026 and 52192632)the Fundamental Research Funds for the Central Universities(Grant No.YWF-22-L-1119)。
文摘This paper proposes a gradient conformal design technique to modify the multi-directional stiffness characteristics of 3D printed chiral metamaterials,using various airfoil shapes.The method ensures the integrity of chiral cell nodal circles while improving load transmission efficiency and enhancing manufacturing precision for 3D printing applications.A parametric design framework,integrating finite element analysis and optimization modules,is developed to enhance the wing’s multidirectional stiffness.The optimization process demonstrates that the distribution of chiral structural ligaments and nodal circles significantly affects wing deformation.The stiffness gradient optimization results reveal a variation of over 78%in tail stiffness performance between the best and worst parameter combinations.Experimental outcomes suggest that this strategy can develop metamaterials with enhanced deformability,offering a promising approach for designing morphing wings.
文摘Although General Relativity is the classic example of a physical theory based on differential geometry, the momentum tensor is the only part of the field equation that is not derived from or interpreted with differential geometry. This work extends General Relativity and Einstein-Cartan theory by augmenting the Poincaré group with projective (special) conformal transformations, which are translations at conformal infinity. Momentum becomes a part of the differential geometry of spacetime. The Lie algebra of these transformations is represented by vectorfields on an associated Minkowski fiber space. Variation of projective conformal scalar curvature generates a 2-index tensor that serves as linear momentum in the field equations of General Relativity. The computation yields a constructive realization of Mach’s principle: local inertia is determined by local motion relative to mass at conformal infinity in each fiber. The vectorfields have a cellular structure that is similar to that of turbulent fluids.
文摘This paper discusses the feasibility of thin-shell wormholes in spacetimes of embedding class one admitting a one-parameter group of conformal motions. It is shown that the surface energy density σis positive, while the surface pressure is negative, resulting in , thereby signaling a violation of the null energy condition, a necessary condition for holding a wormhole open. For a Morris-Thorne wormhole, matter that violates the null energy condition is referred to as “exotic”. For the thin-shell wormholes in this paper, however, the violation has a physical explanation since it is a direct consequence of the embedding theory in conjunction with the assumption of conformal symmetry. These properties avoid the need to hypothesize the existence of the highly problematical exotic matter.
