Background: Obesity, particularly abdominal obesity, is a well-established risk factor for arterial stiffness (AS) and cardiovascular diseases. A Body Shape Index (ABSI) is a novel anthropometric measure designed to a...Background: Obesity, particularly abdominal obesity, is a well-established risk factor for arterial stiffness (AS) and cardiovascular diseases. A Body Shape Index (ABSI) is a novel anthropometric measure designed to assess abdominal obesity, yet its association with AS remains inconclusive. This study aims to investigate the relationship between ABSI and AS indicators in a general population. Methods: This cross-sectional study included 721 participants from the general population of Dali, Yunnan Province, China. ABSI was calculated using a standardized formula. Univariate and multivariate linear regression analyses were performed to examine the associations between ABSI and AS indicators, including brachial-ankle pulse wave velocity (ba-PWV) and carotid-femoral pulse wave velocity (cf-PWV). Results: Higher ABSI tertiles were significantly associated with increased ba-PWV and cf-PWV compared to the lowest tertile (P ≤ 0.007). However, after adjusting for potential confounders, these associations became non-significant (P ≥ 0.058), suggesting that ABSI is not an independent predictor of AS. Conclusions: The initial association between ABSI and AS was attenuated after covariate adjustment, suggesting ABSI is not an independent AS marker. Further research is warranted to understand the complex interactions between ABSI and other cardiovascular risk factors and its potential role in AS risk assessment.展开更多
Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMM...Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMMA content on their transparency and pulse shape discrimination(PSD)ability is investigated.The fabricated samples,comprising a polystyrene(PS)-PMMA matrix,30.0 wt%2,5-diphenyloxazole(PPO),and 0.2 wt%9,10-diphenylanthracene(DPA),exhibit high transparency with transmissivity ranging from 70.0 to 90.0%(above 415.0 nm)and demonstrate excellent n/γdiscrimination capability.Transparency increased with increasing PMMA content across the entire visible light spectrum.However,the PSD performance gradually deteriorated when the aromatic matrix was replaced with PMMA.The scintillator containing 20.0 wt%PMMA demonstrated the best stability concerning PSD properties and relative light yields.展开更多
The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal de...The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal design,by considering material performance,cost,and structural safety.The design approaches aim to reduce the built environment’s energy use and carbon emissions.This comprehensive review examines optimization techniques,including size,shape,topology,and multi-objective approaches,by integrating these methodologies.The trends and advancements that contribute to developing more efficient,cost-effective,and reliable structural designs were identified.The review also discusses emerging technologies,such as machine learning applications with different optimization techniques.Optimization of truss,frame,tensegrity,reinforced concrete,origami,pantographic,and adaptive structures are covered and discussed.Optimization techniques are explained,including metaheuristics,genetic algorithm,particle swarm,ant-colony,harmony search algorithm,and their applications with mentioned structure types.Linear and non-linear structures,including geometric and material nonlinearity,are distinguished.The role of optimization in active structures,structural design,seismic design,form-finding,and structural control is taken into account,and the most recent techniques and advancements are mentioned.展开更多
Shape Memory Polymers(SMPs)need to be given a temporary shape in advance to realize the shape memory process,but the manual shaping process is cumbersome and has low precision.Here,we propose a universal applicable me...Shape Memory Polymers(SMPs)need to be given a temporary shape in advance to realize the shape memory process,but the manual shaping process is cumbersome and has low precision.Here,we propose a universal applicable method for 4D printing self-folding SMPs by pre-stretching extruded filaments during 3D printing,the temporary shape of the SMPs were designed and fixed during 3D printing.Prepared samples can automatically perform shape memory process under stimulation without manual temporary shape programming process.Furthermore,using carbon ink as a photothermal conversion agent enables the 4D printing SMPs to have thermal and light response characteristics.In addition,some bionic applications of self-folding SMPs were demonstrated,such as self-morphing grasper,DNA double helix structures,programmable sequential switching mimosa,self-folding box and human hand.The combination of SMP and 3D printing fully takes advantage of 4D printing technology,and the self-folding SMPs show great potential applications in the fields of tissue engineering scaffold,self-folding robots,self-assembly system and so on.展开更多
Background Three-dimensional(3D)shape representation using mesh data is essential in various applications,such as virtual reality and simulation technologies.Current methods for extracting features from mesh edges or ...Background Three-dimensional(3D)shape representation using mesh data is essential in various applications,such as virtual reality and simulation technologies.Current methods for extracting features from mesh edges or faces struggle with complex 3D models because edge-based approaches miss global contexts and face-based methods overlook variations in adjacent areas,which affects the overall precision.To address these issues,we propose the Feature Discrimination and Context Propagation Network(FDCPNet),which is a novel approach that synergistically integrates local and global features in mesh datasets.Methods FDCPNet is composed of two modules:(1)the Feature Discrimination Module,which employs an attention mechanism to enhance the identification of key local features,and(2)the Context Propagation Module,which enriches key local features by integrating global contextual information,thereby facilitating a more detailed and comprehensive representation of crucial areas within the mesh model.Results Experiments on popular datasets validated the effectiveness of FDCPNet,showing an improvement in the classification accuracy over the baseline MeshNet.Furthermore,even with reduced mesh face numbers and limited training data,FDCPNet achieved promising results,demonstrating its robustness in scenarios of variable complexity.展开更多
Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimen...Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.展开更多
Neural implicit representation(NIR)has attracted significant attention in 3D shape representation for its efficiency,generalizability,and flexibility compared with traditional explicit representations.Previous works u...Neural implicit representation(NIR)has attracted significant attention in 3D shape representation for its efficiency,generalizability,and flexibility compared with traditional explicit representations.Previous works usually parameterize shapes with neural feature grids/volumes,which prove to be inefficient for the discrete position constraints of the representations.While recent advances make it possible to optimize continuous positions for the latent codes,they still lack self-adaptability to represent various kinds of shapes well.In this paper,we introduce a hierarchical adaptive code cloud(HACC)model to achieve an accurate and compact implicit 3D shape representation.Specifically,we begin by assigning adaptive influence fields and dynamic positions to latent codes,which are optimizable during training,and propose an adaptive aggregation function to fuse the contributions of candidate latent codes with respect to query points.In addition,these basic modules are stacked hierarchically with gradually narrowing influence field thresholds and,therefore,heuristically forced to focus on capturing finer structures at higher levels.These formulations greatly improve the distribution and effectiveness of local latent codes and reconstruct shapes from coarse to fine with high accuracy.Extensive qualitative and quantitative evaluations both on single-shape reconstruction and large-scale dataset representation tasks demonstrate the superiority of our method over state-of-the-art approaches.展开更多
To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with...To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with rectangular,circular,and D-shaped holes.Asθincreases from 0°to 60°in the rectangular hole,the left failure location shifts from the left corner to the left sidewall,the left corner,and then the floor,while the right failure location shifts from the right corner to the right sidewall,right roof corner,and then the roof.Furthermore,the initial failure vertical stress first decreases and then increases.In comparison,the failure severity in the rectangular hole decreases for variousθvalues as 30°>45°>60°>0°.With increasingθ,the fractal dimension(D)of rock slices first increases and then decreases.For the rectangular and D-shaped holes,whenθ=0°,30°,and 90°,D for the rectangular hole is less than that of the D-shaped hole.Whenθ=45°and 60°,D for the rectangular hole is greater than that of the D-shaped hole.Theoretical analysis indicates that the stress concentration at the rectangular and D-shaped corners is greater than the other areas.The failure location rotates with the rotation ofθ,and the failure occurs on the side with a high concentration of compressive stress,while the side with the tensile and compressive stresses remains relatively stable.Therefore,the fundamental reason for the rotation of failure location is the rotation of stress concentration,and the external influencing factor is the rotation ofθ.展开更多
Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of ...Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of Zn O:Ga(GZO)in nuclear energy is particularly significant and fascinating at the fundamental level,enabling neutron/gamma discrimination while preserving the response time properties of the single crystal in sub-nanoseconds,maximizing the effective counting rate of the pulsed radiation field.In this study,the single-particle waveform discrimination characteristics of GZO were evaluated for five charged particles(α,β,H^(+),Li^(+),and O^(8+)and two prevalent uncharged particles(neutrons and gamma rays).Based on the timecorrelation single-photon counting(TCSPC)method,the luminescence decay time constants of the charged particles in the GZO crystal were determined as follows:1.21 ns for H^(+),1.50 ns for Li^(+),1.70 ns for O^(8+),1.56 ns forαparticles,and 1.09 ns forβparticles.Visible differences in the excitation time spectra curves were observed.Using the conventional time-domain or frequency-domain waveform discrimination techniques,waveform discrimination of 14.9 Me V neutrons and secondary gamma rays generated by the CPNG-6 device based on GZO scintillation was successfully implemented.The neutron signal constituted 77.93%of the total,indicating that GZO exhibited superior neutron/gamma discrimination sensitivity compared with that of a commercial stilbene crystal.Using the neutron/gamma screening outcomes,we reconstructed the voltage pulse height,charge height,and neutron multiplication time spectra of the pulsed neutron radiation field.The reconstructed neutron multiplication time spectrum exhibited a deviation of less than 3%relative to the result obtained using a commercial stilbene scintillator.This is the first report in the open literature on the neutron/gamma discrimination and reconstruction of Zn O pulsed radiation-field information.展开更多
The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope ...The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.展开更多
A scheme based on irregular V-shaped silicon nanoantennas is proposed to optimize transverse unidirectional scattering under plane wave irradiation.Traditional methods of designing regular shapes offer fewer parameter...A scheme based on irregular V-shaped silicon nanoantennas is proposed to optimize transverse unidirectional scattering under plane wave irradiation.Traditional methods of designing regular shapes offer fewer parameters and higher search efficiency.However,due to the limitations of regular shapes,it is challenging to meet high-precision design requirements.Irregular shape design allows for a broader range of adjustments,but the complexity of shape parameters leads to lower search efficiency and a higher likelihood of converging to local optima.展开更多
Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been conducted.However,the current reports about TPMS porous structure...Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been conducted.However,the current reports about TPMS porous structures highly rely on the implicit equation,which limited the design flexibility.In this work,novel shell-based TPMS structures were designed and fabricated by laser powder bed fusion.The comparisons of manufacturability,mechanical properties,and shape recovery responses between traditional solid-based and novel shell-based TPMS structures were evaluated.Results indicated that the shell-based TPMS porous structures possessed larger Young's moduli and higher compressive strengths.Specifically,Diamond shell structure possessed the highest Young's moduli of 605.8±24.5MPa,while Gyroid shell structure possessed the highest compressive strength of 43.90±3.32 MPa.In addition,because of the larger specific surface area,higher critical stress to induce martensite transformation,and lower austenite finish temperature,the Diamond shell porous structure exhibited much higher shape recovery performance(only 0.1%residual strain left at pre-strains of 6%)than other porous structures.These results substantially uncover the effects of structural topology on the mechanical properties and shape recovery responses of NiTi shape memory alloy scaffolds,and confirm the effectiveness of this novel structural design method.This research can provide guidance for the structural design application of NiTi porous scaffolds in bone implants.展开更多
The martensitic transformation temperature is the basis for the application of shape memory alloys(SMAs),and the ability to quickly and accurately predict the transformation temperature of SMAs has very important prac...The martensitic transformation temperature is the basis for the application of shape memory alloys(SMAs),and the ability to quickly and accurately predict the transformation temperature of SMAs has very important practical significance.In this work,machine learning(ML)methods were utilized to accelerate the search for shape memory alloys with targeted properties(phase transition temperature).A group of component data was selected to design shape memory alloys using reverse design method from numerous unexplored data.Component modeling and feature modeling were used to predict the phase transition temperature of the shape memory alloys.The experimental results of the shape memory alloys were obtained to verify the effectiveness of the support vector regression(SVR)model.The results show that the machine learning model can obtain target materials more efficiently and pertinently,and realize the accurate and rapid design of shape memory alloys with specific target phase transition temperature.On this basis,the relationship between phase transition temperature and material descriptors is analyzed,and it is proved that the key factors affecting the phase transition temperature of shape memory alloys are based on the strength of the bond energy between atoms.This work provides new ideas for the controllable design and performance optimization of Cu-based shape memory alloys.展开更多
The compaction quality of subgrade filler strongly affects subgrade settlement.The main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on th...The compaction quality of subgrade filler strongly affects subgrade settlement.The main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse particles.First,an improved Viola-Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade filler.Shape indexes of 2D subgrade filler are then computed and statistically analyzed.Finally,numerical simulations are performed to quantitatively investigate the effects of the aspect ratio(AR)and interparticle friction coefficient(μ)on the macro-and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method(DEM).The results show that with the increasing AR,the coarse particles are narrower,leading to the increasing movement of fine particles during compaction,which indicates that it is difficult for slender coarse particles to inhibit the migration of fine particles.Moreover,the average displacement of particles is strongly influenced by the AR,indicating that their occlusion under power relies on particle shapes.The dis-placement and velocity of fine particles are much greater than those of the coarse particles,which shows that compaction is primarily a migration of fine particles.Under the cyclic load,the interparticle friction coefficientμhas little effect on the internal structure of the sample;under the quasi-static loads,however,the increase inμwill lead to a significant increase in the porosity of the sample.This study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.展开更多
Rice(Oryza sativa)plant architecture and grain shape,which determine grain quality and yield,are modulatedby auxin and brassinosteroid via regulation of cell elongation and proliferation.We review the signaltransducti...Rice(Oryza sativa)plant architecture and grain shape,which determine grain quality and yield,are modulatedby auxin and brassinosteroid via regulation of cell elongation and proliferation.We review the signaltransduction of these hormones and the crosstalk between their signals on the regulation of rice plantarchitecture and grain shape.展开更多
The occurrence of blockages of trash intercepting net in nuclear power plant due to marine biofouling has become increasingly frequent,leading to significant changes in the mechanical state.This paper establishes a CF...The occurrence of blockages of trash intercepting net in nuclear power plant due to marine biofouling has become increasingly frequent,leading to significant changes in the mechanical state.This paper establishes a CFD(Computational Fluid Dynamics)model to simulate the hydrodynamic forces of trash intercepting net under the action of regular waves.The porous media model is used to calculate the hydrodynamic forces,and the maximum mooring load is also evaluated.The simplified calculation method considering the different curved shape based on the flat nets are proposed,and the influences of wave parameters,solidity,and curved shape are investigated.The results indicate that under the regular wave conditions,as the solidity increases,the phenomenon of secondary wave peaks becomes more pronounced.The horizontal wave force reduction coefficient follows a three-piecewise linear relationship with the non-dimensional deformation level of curved shape.The trash intercepting net exhibits more potent scattering effects on short-wave conditions,displaying significant non-linear characteristics.The deformation level of the trash intercepting net is a significant factor influencing the mooring load.展开更多
文摘Background: Obesity, particularly abdominal obesity, is a well-established risk factor for arterial stiffness (AS) and cardiovascular diseases. A Body Shape Index (ABSI) is a novel anthropometric measure designed to assess abdominal obesity, yet its association with AS remains inconclusive. This study aims to investigate the relationship between ABSI and AS indicators in a general population. Methods: This cross-sectional study included 721 participants from the general population of Dali, Yunnan Province, China. ABSI was calculated using a standardized formula. Univariate and multivariate linear regression analyses were performed to examine the associations between ABSI and AS indicators, including brachial-ankle pulse wave velocity (ba-PWV) and carotid-femoral pulse wave velocity (cf-PWV). Results: Higher ABSI tertiles were significantly associated with increased ba-PWV and cf-PWV compared to the lowest tertile (P ≤ 0.007). However, after adjusting for potential confounders, these associations became non-significant (P ≥ 0.058), suggesting that ABSI is not an independent predictor of AS. Conclusions: The initial association between ABSI and AS was attenuated after covariate adjustment, suggesting ABSI is not an independent AS marker. Further research is warranted to understand the complex interactions between ABSI and other cardiovascular risk factors and its potential role in AS risk assessment.
基金supported by the National Natural Science Foundation of China(No.12027813)the fund of National Innovation Center of Radiation Application of China(Nos.KFZC2020020501,KFZC2021010101).
文摘Polymethyl methacrylate(PMMA)is an optically transparent thermoplastic with favorable processing conditions.In this study,a series of plastic scintillators are prepared via thermal polymerization,and the impact of PMMA content on their transparency and pulse shape discrimination(PSD)ability is investigated.The fabricated samples,comprising a polystyrene(PS)-PMMA matrix,30.0 wt%2,5-diphenyloxazole(PPO),and 0.2 wt%9,10-diphenylanthracene(DPA),exhibit high transparency with transmissivity ranging from 70.0 to 90.0%(above 415.0 nm)and demonstrate excellent n/γdiscrimination capability.Transparency increased with increasing PMMA content across the entire visible light spectrum.However,the PSD performance gradually deteriorated when the aromatic matrix was replaced with PMMA.The scintillator containing 20.0 wt%PMMA demonstrated the best stability concerning PSD properties and relative light yields.
文摘The optimization of civil engineering structures is critical for enhancing structural performance and material efficiency in engineering applications.Structural optimization approaches seek to determine the optimal design,by considering material performance,cost,and structural safety.The design approaches aim to reduce the built environment’s energy use and carbon emissions.This comprehensive review examines optimization techniques,including size,shape,topology,and multi-objective approaches,by integrating these methodologies.The trends and advancements that contribute to developing more efficient,cost-effective,and reliable structural designs were identified.The review also discusses emerging technologies,such as machine learning applications with different optimization techniques.Optimization of truss,frame,tensegrity,reinforced concrete,origami,pantographic,and adaptive structures are covered and discussed.Optimization techniques are explained,including metaheuristics,genetic algorithm,particle swarm,ant-colony,harmony search algorithm,and their applications with mentioned structure types.Linear and non-linear structures,including geometric and material nonlinearity,are distinguished.The role of optimization in active structures,structural design,seismic design,form-finding,and structural control is taken into account,and the most recent techniques and advancements are mentioned.
基金supported by the National Natural Science Foundation of China(52175271,52021003,52375287)Science and Technology Development Plan Project of Jilin Province(20210509047RQ,20230508041RC).
文摘Shape Memory Polymers(SMPs)need to be given a temporary shape in advance to realize the shape memory process,but the manual shaping process is cumbersome and has low precision.Here,we propose a universal applicable method for 4D printing self-folding SMPs by pre-stretching extruded filaments during 3D printing,the temporary shape of the SMPs were designed and fixed during 3D printing.Prepared samples can automatically perform shape memory process under stimulation without manual temporary shape programming process.Furthermore,using carbon ink as a photothermal conversion agent enables the 4D printing SMPs to have thermal and light response characteristics.In addition,some bionic applications of self-folding SMPs were demonstrated,such as self-morphing grasper,DNA double helix structures,programmable sequential switching mimosa,self-folding box and human hand.The combination of SMP and 3D printing fully takes advantage of 4D printing technology,and the self-folding SMPs show great potential applications in the fields of tissue engineering scaffold,self-folding robots,self-assembly system and so on.
基金Supported by the National Key R&D Program of China(2022YFC3803600).
文摘Background Three-dimensional(3D)shape representation using mesh data is essential in various applications,such as virtual reality and simulation technologies.Current methods for extracting features from mesh edges or faces struggle with complex 3D models because edge-based approaches miss global contexts and face-based methods overlook variations in adjacent areas,which affects the overall precision.To address these issues,we propose the Feature Discrimination and Context Propagation Network(FDCPNet),which is a novel approach that synergistically integrates local and global features in mesh datasets.Methods FDCPNet is composed of two modules:(1)the Feature Discrimination Module,which employs an attention mechanism to enhance the identification of key local features,and(2)the Context Propagation Module,which enriches key local features by integrating global contextual information,thereby facilitating a more detailed and comprehensive representation of crucial areas within the mesh model.Results Experiments on popular datasets validated the effectiveness of FDCPNet,showing an improvement in the classification accuracy over the baseline MeshNet.Furthermore,even with reduced mesh face numbers and limited training data,FDCPNet achieved promising results,demonstrating its robustness in scenarios of variable complexity.
基金financial support from the National Key R&D Program of China(Nos.2023YFB3811400,2022YFB3806000)the National Natural Science Foundation of China(Nos.12074314,52202370,52332006)+2 种基金the Aeronautical Science Foundation of China(No.20230018053007)the Science and Technology New Star Program of Shaanxi Province(No.2023KJXX-148)the Fundamental Research Funds for the Central Universities,and China Postdoctoral Science Foundation(No.2023T160359).
文摘Reconfigurable metamaterials significantly expand the application scenarios and operating frequency range of metamaterials,making them promising candidates for use in smart tunable device.Here,we propose and experimentally demonstrate that integrating metamaterial design principles with the intrinsic features of natural materials can engineer thermal smart metadevices.Tunable extraordinary optical transmission like(EOT-like)phenomena have been achieved in the microwave regime using shape memory alloy(SMA).The strongly localized fields generated by designed metadevices,combined with the intense interference of incident waves,enhance transmission through subwavelength apertures.Leveraging the temperature-responsive properties of SMA,the morphology of the metadevice can be recontructed,thereby modifying its response to electromagnetic waves.The experiments demonstrated control over the operating frequency and transmission amplitude of EOT-like behavior,achieving a maximum transmission enhancement factor of 126.Furthermore,the metadevices with modular design enable the realization of multiple functions with independent control have been demonstrated.The proposed SMA-based metamaterials offer advantages in terms of miniaturization,easy processing,and high design flexibility.They may have potential applications in microwave devices requiring temperature control,such as sensing and monitoring.
基金supported by the National Natural Science Foundation of China(Nos.62001213 and 62025108).
文摘Neural implicit representation(NIR)has attracted significant attention in 3D shape representation for its efficiency,generalizability,and flexibility compared with traditional explicit representations.Previous works usually parameterize shapes with neural feature grids/volumes,which prove to be inefficient for the discrete position constraints of the representations.While recent advances make it possible to optimize continuous positions for the latent codes,they still lack self-adaptability to represent various kinds of shapes well.In this paper,we introduce a hierarchical adaptive code cloud(HACC)model to achieve an accurate and compact implicit 3D shape representation.Specifically,we begin by assigning adaptive influence fields and dynamic positions to latent codes,which are optimizable during training,and propose an adaptive aggregation function to fuse the contributions of candidate latent codes with respect to query points.In addition,these basic modules are stacked hierarchically with gradually narrowing influence field thresholds and,therefore,heuristically forced to focus on capturing finer structures at higher levels.These formulations greatly improve the distribution and effectiveness of local latent codes and reconstruct shapes from coarse to fine with high accuracy.Extensive qualitative and quantitative evaluations both on single-shape reconstruction and large-scale dataset representation tasks demonstrate the superiority of our method over state-of-the-art approaches.
基金supported by the National Natural Science Foundation of China (Grant Nos.52304227 and 52104133)Scientific and Technological Research Platform for Disaster Prevention and Control of Deep Coal Mining (Anhui University of Science and Technology) (Grant No.DPDCM2208).
文摘To investigate the effects of the maximum principal stress direction(θ)and cross-section shape on the failure characteristics of sandstone,true-triaxial compression experiments were conducted using cubic samples with rectangular,circular,and D-shaped holes.Asθincreases from 0°to 60°in the rectangular hole,the left failure location shifts from the left corner to the left sidewall,the left corner,and then the floor,while the right failure location shifts from the right corner to the right sidewall,right roof corner,and then the roof.Furthermore,the initial failure vertical stress first decreases and then increases.In comparison,the failure severity in the rectangular hole decreases for variousθvalues as 30°>45°>60°>0°.With increasingθ,the fractal dimension(D)of rock slices first increases and then decreases.For the rectangular and D-shaped holes,whenθ=0°,30°,and 90°,D for the rectangular hole is less than that of the D-shaped hole.Whenθ=45°and 60°,D for the rectangular hole is greater than that of the D-shaped hole.Theoretical analysis indicates that the stress concentration at the rectangular and D-shaped corners is greater than the other areas.The failure location rotates with the rotation ofθ,and the failure occurs on the side with a high concentration of compressive stress,while the side with the tensile and compressive stresses remains relatively stable.Therefore,the fundamental reason for the rotation of failure location is the rotation of stress concentration,and the external influencing factor is the rotation ofθ.
基金supported by the National Natural Science Foundation of China(Nos.12205370,62204198,12305205,and 12105230)Young Talents Promotion Program of Shaanxi Provincial Science and Technology Association(No.20220514)。
文摘Doping with Ga effectively enhances the crystal quality and optical detection efficiency of zinc oxide(Zn O)single crystals,which has attracted considerable research interest in radiation detection.The application of Zn O:Ga(GZO)in nuclear energy is particularly significant and fascinating at the fundamental level,enabling neutron/gamma discrimination while preserving the response time properties of the single crystal in sub-nanoseconds,maximizing the effective counting rate of the pulsed radiation field.In this study,the single-particle waveform discrimination characteristics of GZO were evaluated for five charged particles(α,β,H^(+),Li^(+),and O^(8+)and two prevalent uncharged particles(neutrons and gamma rays).Based on the timecorrelation single-photon counting(TCSPC)method,the luminescence decay time constants of the charged particles in the GZO crystal were determined as follows:1.21 ns for H^(+),1.50 ns for Li^(+),1.70 ns for O^(8+),1.56 ns forαparticles,and 1.09 ns forβparticles.Visible differences in the excitation time spectra curves were observed.Using the conventional time-domain or frequency-domain waveform discrimination techniques,waveform discrimination of 14.9 Me V neutrons and secondary gamma rays generated by the CPNG-6 device based on GZO scintillation was successfully implemented.The neutron signal constituted 77.93%of the total,indicating that GZO exhibited superior neutron/gamma discrimination sensitivity compared with that of a commercial stilbene crystal.Using the neutron/gamma screening outcomes,we reconstructed the voltage pulse height,charge height,and neutron multiplication time spectra of the pulsed neutron radiation field.The reconstructed neutron multiplication time spectrum exhibited a deviation of less than 3%relative to the result obtained using a commercial stilbene scintillator.This is the first report in the open literature on the neutron/gamma discrimination and reconstruction of Zn O pulsed radiation-field information.
基金Funded by the National Natural Science Foundation of China Academy of Engineering Physics and Jointly Setup"NSAF"Joint Fund(No.U1430119)。
文摘The multi-scale modeling combined with the cohesive zone model(CZM)and the molecular dynamics(MD)method were preformed to simulate the crack propagation in NiTi shape memory alloys(SMAs).The metallographic microscope and image processing technology were employed to achieve a quantitative grain size distribution of NiTi alloys so as to provide experimental data for molecular dynamics modeling at the atomic scale.Considering the size effect of molecular dynamics model on material properties,a reasonable modeling size was provided by taking into account three characteristic dimensions from the perspective of macro,meso,and micro scales according to the Buckinghamπtheorem.Then,the corresponding MD simulation on deformation and fracture behavior was investigated to derive a parameterized traction-separation(T-S)law,and then it was embedded into cohesive elements of finite element software.Thus,the crack propagation behavior in NiTi alloys was reproduced by the finite element method(FEM).The experimental results show that the predicted initiation fracture toughness is in good agreement with experimental data.In addition,it is found that the dynamics initiation fracture toughness increases with decreasing grain size and increasing loading velocity.
基金supported by the National Natural Science Foundation of China(Nos.62475121 and 62335012)。
文摘A scheme based on irregular V-shaped silicon nanoantennas is proposed to optimize transverse unidirectional scattering under plane wave irradiation.Traditional methods of designing regular shapes offer fewer parameters and higher search efficiency.However,due to the limitations of regular shapes,it is challenging to meet high-precision design requirements.Irregular shape design allows for a broader range of adjustments,but the complexity of shape parameters leads to lower search efficiency and a higher likelihood of converging to local optima.
基金Supported by Natural and Science Foundation of China(Grant Nos.52275331,52201041,52305360)Guangdong Provincial Key-Area Research and Development Program of China(Grant No.2020B090923001)+3 种基金National Key Research and Development Program of China(Grant No.2023YFB4604800)Hubei Provincial Key Research and Development Program of China(Grant No.2022BAA011)Academic Frontier Youth Team at Huazhong University of Science and Technology of China(Grant No.2018QYTD04)Hong Kong Scholars Program of China(Grant No.XJ2022014)。
文摘Based on the advantages of triply periodic minimal surface(TPMS)porous structures,extensive research on NiTi shape memory alloy TPMS scaffolds has been conducted.However,the current reports about TPMS porous structures highly rely on the implicit equation,which limited the design flexibility.In this work,novel shell-based TPMS structures were designed and fabricated by laser powder bed fusion.The comparisons of manufacturability,mechanical properties,and shape recovery responses between traditional solid-based and novel shell-based TPMS structures were evaluated.Results indicated that the shell-based TPMS porous structures possessed larger Young's moduli and higher compressive strengths.Specifically,Diamond shell structure possessed the highest Young's moduli of 605.8±24.5MPa,while Gyroid shell structure possessed the highest compressive strength of 43.90±3.32 MPa.In addition,because of the larger specific surface area,higher critical stress to induce martensite transformation,and lower austenite finish temperature,the Diamond shell porous structure exhibited much higher shape recovery performance(only 0.1%residual strain left at pre-strains of 6%)than other porous structures.These results substantially uncover the effects of structural topology on the mechanical properties and shape recovery responses of NiTi shape memory alloy scaffolds,and confirm the effectiveness of this novel structural design method.This research can provide guidance for the structural design application of NiTi porous scaffolds in bone implants.
基金financially supported by the National Natural Science Foundation of China(No.51974028)。
文摘The martensitic transformation temperature is the basis for the application of shape memory alloys(SMAs),and the ability to quickly and accurately predict the transformation temperature of SMAs has very important practical significance.In this work,machine learning(ML)methods were utilized to accelerate the search for shape memory alloys with targeted properties(phase transition temperature).A group of component data was selected to design shape memory alloys using reverse design method from numerous unexplored data.Component modeling and feature modeling were used to predict the phase transition temperature of the shape memory alloys.The experimental results of the shape memory alloys were obtained to verify the effectiveness of the support vector regression(SVR)model.The results show that the machine learning model can obtain target materials more efficiently and pertinently,and realize the accurate and rapid design of shape memory alloys with specific target phase transition temperature.On this basis,the relationship between phase transition temperature and material descriptors is analyzed,and it is proved that the key factors affecting the phase transition temperature of shape memory alloys are based on the strength of the bond energy between atoms.This work provides new ideas for the controllable design and performance optimization of Cu-based shape memory alloys.
基金This work was supported by the National Key R&D Program‘Transportation Infrastructure’project(No.2022YFB2603400).
文摘The compaction quality of subgrade filler strongly affects subgrade settlement.The main objective of this research is to analyze the macro-and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse particles.First,an improved Viola-Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade filler.Shape indexes of 2D subgrade filler are then computed and statistically analyzed.Finally,numerical simulations are performed to quantitatively investigate the effects of the aspect ratio(AR)and interparticle friction coefficient(μ)on the macro-and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method(DEM).The results show that with the increasing AR,the coarse particles are narrower,leading to the increasing movement of fine particles during compaction,which indicates that it is difficult for slender coarse particles to inhibit the migration of fine particles.Moreover,the average displacement of particles is strongly influenced by the AR,indicating that their occlusion under power relies on particle shapes.The dis-placement and velocity of fine particles are much greater than those of the coarse particles,which shows that compaction is primarily a migration of fine particles.Under the cyclic load,the interparticle friction coefficientμhas little effect on the internal structure of the sample;under the quasi-static loads,however,the increase inμwill lead to a significant increase in the porosity of the sample.This study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.
基金the National Natural Science Foundation of China(32370248)the Jiangsu Seed Industry Revitalization Project(JBGS[2021]001)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Rice(Oryza sativa)plant architecture and grain shape,which determine grain quality and yield,are modulatedby auxin and brassinosteroid via regulation of cell elongation and proliferation.We review the signaltransduction of these hormones and the crosstalk between their signals on the regulation of rice plantarchitecture and grain shape.
基金financially supported by National Natural Science Foundation of China(Grant No.52201311)Fundamental Research Funds for the Central Universities.
文摘The occurrence of blockages of trash intercepting net in nuclear power plant due to marine biofouling has become increasingly frequent,leading to significant changes in the mechanical state.This paper establishes a CFD(Computational Fluid Dynamics)model to simulate the hydrodynamic forces of trash intercepting net under the action of regular waves.The porous media model is used to calculate the hydrodynamic forces,and the maximum mooring load is also evaluated.The simplified calculation method considering the different curved shape based on the flat nets are proposed,and the influences of wave parameters,solidity,and curved shape are investigated.The results indicate that under the regular wave conditions,as the solidity increases,the phenomenon of secondary wave peaks becomes more pronounced.The horizontal wave force reduction coefficient follows a three-piecewise linear relationship with the non-dimensional deformation level of curved shape.The trash intercepting net exhibits more potent scattering effects on short-wave conditions,displaying significant non-linear characteristics.The deformation level of the trash intercepting net is a significant factor influencing the mooring load.
