Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of...Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.展开更多
The ubiquitous adoption of mobile devices as essential platforms for sensitive data transmission has heightened the demand for secure client-server communication.Although various authentication and key agreement proto...The ubiquitous adoption of mobile devices as essential platforms for sensitive data transmission has heightened the demand for secure client-server communication.Although various authentication and key agreement protocols have been developed,current approaches are constrained by homogeneous cryptosystem frameworks,namely public key infrastructure(PKI),identity-based cryptography(IBC),or certificateless cryptography(CLC),each presenting limitations in client-server architectures.Specifically,PKI incurs certificate management overhead,IBC introduces key escrow risks,and CLC encounters cross-system interoperability challenges.To overcome these shortcomings,this study introduces a heterogeneous signcryption-based authentication and key agreement protocol that synergistically integrates IBC for client operations(eliminating PKI’s certificate dependency)with CLC for server implementation(mitigating IBC’s key escrow issue while preserving efficiency).Rigorous security analysis under the mBR(modified Bellare-Rogaway)model confirms the protocol’s resistance to adaptive chosen-ciphertext attacks.Quantitative comparisons demonstrate that the proposed protocol achieves 10.08%–71.34%lower communication overhead than existing schemes across multiple security levels(80-,112-,and 128-bit)compared to existing protocols.展开更多
A rapidly growing field is piezoresistive sensor for accurate respiration rate monitoring to suppress the worldwide respiratory illness.However,a large neglected issue is the sensing durability and accuracy without in...A rapidly growing field is piezoresistive sensor for accurate respiration rate monitoring to suppress the worldwide respiratory illness.However,a large neglected issue is the sensing durability and accuracy without interference since the expiratory pressure always coupled with external humidity and temperature variations,as well as mechanical motion artifacts.Herein,a robust and biodegradable piezoresistive sensor is reported that consists of heterogeneous MXene/cellulose-gelation sensing layer and Ag-based interdigital electrode,featuring customizable cylindrical interface arrangement and compact hierarchical laminated architecture for collectively regulating the piezoresistive response and mechanical robustness,thereby realizing the long-term breath-induced pressure detection.Notably,molecular dynamics simulations reveal the frequent angle inversion and reorientation of MXene/cellulose in vacuum filtration,driven by shear forces and interfacial interactions,which facilitate the establishment of hydrogen bonds and optimize the architecture design in sensing layer.The resultant sensor delivers unprecedented collection features of superior stability for off-axis deformation(0-120°,~2.8×10^(-3) A)and sensing accuracy without crosstalk(humidity 50%-100%and temperature 30-80).Besides,the sensor-embedded mask together with machine learning models is achieved to train and classify the respiration status for volunteers with different ages(average prediction accuracy~90%).It is envisioned that the customizable architecture design and sensor paradigm will shed light on the advanced stability of sustainable electronics and pave the way for the commercial application in respiratory monitory.展开更多
Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,th...Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.展开更多
With the increasing complexity of malware attack techniques,traditional detection methods face significant challenges,such as privacy preservation,data heterogeneity,and lacking category information.To address these i...With the increasing complexity of malware attack techniques,traditional detection methods face significant challenges,such as privacy preservation,data heterogeneity,and lacking category information.To address these issues,we propose Federated Dynamic Prototype Learning(FedDPL)for malware classification by integrating Federated Learning with a specifically designed K-means.Under the Federated Learning framework,model training occurs locally without data sharing,effectively protecting user data privacy and preventing the leakage of sensitive information.Furthermore,to tackle the challenges of data heterogeneity and the lack of category information,FedDPL introduces a dynamic prototype learning mechanism,which adaptively adjusts the clustering prototypes in terms of position and number.Thus,the dependency on predefined category numbers in typical K-means and its variants can be significantly reduced,resulting in improved clustering performance.Theoretically,it provides a more accurate detection of malicious behavior.Experimental results confirm that FedDPL excels in handling malware classification tasks,demonstrating superior accuracy,robustness,and privacy protection.展开更多
Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effectiv...Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.展开更多
To obtain protease-and lipase-producing halotolerant/halophilic strains suitable for shrimp paste(SP)fermentation,the microbial community structure and enzyme-producing microbial species were analyzed and predicted us...To obtain protease-and lipase-producing halotolerant/halophilic strains suitable for shrimp paste(SP)fermentation,the microbial community structure and enzyme-producing microbial species were analyzed and predicted using metagenomics in 3 high-salt samples.Based on the linear salt gradient method,128 strains were screened.Eight halotolerant/halophilic strains highly producing 2 types of enzymes were identified and inoculated into lowsalt SP to assess the heterogeneity of SP.Physicochemical properties of SP indicated that Bacillus subtilis XJ-11,Virgibacillus halodenitrificans XJ-229,Piscibacillus halophilus XY-193,and Bacillus vallismortis HT-73 were more suitable for rapid fermentation of SP.Nutritional analysis showed that SP inoculated with V.halodenitrificans XJ-229 had the highest free amino acid content and SP inoculated with P.halophilus XY-193 had the highest unsaturated fatty acid content.The former had prominent umami,sweetness,and meaty aroma,weak bitterness and fishy flavor,and the closest flavor to the control(CP)based on sensory evaluation and E-nose analysis.A total of 61 volatile compounds were detected in all samples by SPME-GC-MS,of which 32,23,40,24,and 28 were detected in the CP and SP inoculated with B.subtilis XJ-11,V.halodenitrificans XJ-229,P.halophilus XY-193,and B.vallismortis HT-73,respectively,with 12,11,12,9,and 9 key flavor compounds.Among several samples,the highest levels of pyrazines,aldehydes,alcohols,and ketones were found in SP inoculated with B.subtilis XJ-11,V.halodenitrificans XJ-229,P.halophilus XY-193,and B.vallismortis HT-73,respectively.These results suggested that inoculation of different enzyme-producing halotolerant/halophilic strains resulted in differences in SP quality and main flavors.This study provides some references for process control and interpretation of heterogeneous mechanisms in low-salt SP fermented by inoculated strains.展开更多
The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration...The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration of rotorcraft.The aerodynamic interaction of tandem tilt-wing and multi-rotor is investigated based on the CFD method.The aerodynamic effect of multi tilt-rotor is simulated as virtual disk modeling by adding source terms to the Navier-Stokes equations,effectively reducing the calculation time while maintaining the accuracy of aerodynamic interaction calculations.Aerodynamic forces and flow field characteristics of the tandem tilt-wing and multi-rotor under different tilt angles are compared between cases with and without aerodynamic interaction.Furthermore,the differences in aerodynamic forces between dynamic tilt transition and fixed-angle conditions were compared.The results show that the aerodynamic interaction of multi-rotor obviously increases the lift of front tilt-wing at different tilt angles,the wing lift under interaction is increased by more than 40%compared with isolated wing at tilt angle of 15°for the computation in this paper,which is related to the increase of wing flow velocity and the suppression of flow separation caused by multi-rotor;the wing blocking effect will increase rotor thrust,especially near the tilt angles of 30°and 45°;the increases of rear wing lift and rear rotor thrust under aerodynamic interaction are not significant because of suppression by the front wing’s downwash;the unsteady effects during dynamic tilting have a relatively minor impact on aerodynamic interaction,with the aerodynamic forces on the rotors and wings during the dynamic tilting process showing little difference from those under corresponding fixed tilt angles.展开更多
This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consen...This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consensus under average dwell time switching.Then sufficient conditions are derived to guarantee the positive consensus.The gain matrices of the control protocol are described using a matrix decomposition approach and the corresponding computational complexity is reduced by resorting to linear programming and co-positive Lyapunov functions.Finally,two numerical examples are provided to illustrate the results obtained.展开更多
Urban traffic generates massive and diverse data,yet most systems remain fragmented.Current approaches to congestion management suffer from weak data consistency and poor scalability.This study addresses this gap by p...Urban traffic generates massive and diverse data,yet most systems remain fragmented.Current approaches to congestion management suffer from weak data consistency and poor scalability.This study addresses this gap by proposing the Urban Traffic Congestion Unified Metadata Model(UTC-UMM).The goal is to provide a standardized and extensible framework for describing,extracting,and storing multisource traffic data in smart cities.The model defines a two-tier specification that organizes nine core traffic resource classes.It employs an eXtensible Markup Language(XML)Schema that connects general elements with resource-specific elements.This design ensures both syntactic and semantic interoperability across siloed datasets.Extension principles allow new elements or constraints to be introducedwithout breaking backward compatibility.Adistributed pipeline is implemented usingHadoop Distributed File System(HDFS)and HBase.It integrates computer vision for video and natural language processing for text to automate metadata extraction.Optimized row-key designs enable low-latency queries.Performance is tested with the Yahoo!Cloud Serving Benchmark(YCSB),which shows linear scalability and high throughput.The results demonstrate that UTC-UMM can unify heterogeneous traffic data while supporting real-time analytics.The discussion highlights its potential to improve data reuse,portability,and scalability in urban congestion studies.Future research will explore integration with association rulemining and advanced knowledge representation to capture richer spatiotemporal traffic patterns.展开更多
In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In additi...In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In addition,methods for deploying multiple cameras for motion capture of users(e.g.,performers)are widely used in computer graphics.As the need to minimize and optimize the number of cameras grows to reduce costs,various technologies and research approaches focused on Optimal Camera Placement(OCP)are continually being proposed.However,as most existing studies assume homogeneous camera setups,there is a growing demand for studies on heterogeneous camera setups.For instance,technical demands keep emerging in scenarios with minimal camera configurations,especially regarding cost factors,the physical placement of cameras given the spatial structure,and image capture strategies for heterogeneous cameras,such as high-resolution RGB cameras and depth cameras.In this study,we propose a pre-visualization and simulation method for the optimal placement of heterogeneous cameras in XR environments,accounting for both the specifications of heterogeneous cameras(e.g.,field of view)and the physical configuration(e.g.,wall configuration)in real-world spaces.The proposed method performs a visibility analysis of cameras by considering each camera’s field-of-view volume,resolution,and unique characteristics,along with physicalspace constraints.This approach enables the optimal position and rotation of each camera to be recommended,along with the minimum number of cameras required.In the results of our study conducted in heterogeneous camera combinations,the proposed method achieved 81.7%~82.7%coverage of the target visual information using only 2~3 cameras.In contrast,single(or homogeneous)-typed cameras were required to use 11 cameras for 81.6%coverage.Accordingly,we found that camera deployment resources can be reduced with the proposed approaches.展开更多
Background:The golden Syrian hamster is a valuable animal model for studying carcinogenesis,metabolic disorders,cardiovascular diseases,and viral infections due to its biological and pathological similarities to human...Background:The golden Syrian hamster is a valuable animal model for studying carcinogenesis,metabolic disorders,cardiovascular diseases,and viral infections due to its biological and pathological similarities to humans.However,the development of genetically engineered hamsters has lagged behind that of mice and rats,largely because of an embryonic development block at the two-cell stage in vitro.Although CRISPR/Cas9-mediated gene knockout has been achieved in hamsters,precise DNA fragment insertion or conditional knockout(cKO)models have not previously been reported,likely due to technical limitations in embryo manipulation and insufficient efficiency of homology-directed repair(HDR).Methods:In this study,we generated conditional alleles of the ApoF gene in golden Syrian hamsters.A two-cut strategy was applied using Cas9 protein,two sgRNAs,and a single donor plasmid containing exon 2 flanked by loxP sites and two~0.8 kb homology arms.A mixture of Cas9 protein,sgRNAs,and the donor plasmid was microinjected into the pronuclei of one-cell stage hamster embryos.Results:The efficiency of CRISPR/Cas9-mediated loxP knock-in reached up to 27%,and the genetically modified floxed alleles were successfully transmitted through the germline.The functionality of the inserted loxP sites was validated by in vivo Cremediated recombination following local administration of AAV vectors,including AAV-cTnT-Cre in the heart and AAV-CMV-Cre in the brain.Conclusions:To our knowledge,this work represents the first successful establishment of a conditional knockout model in the golden Syrian hamster,providing a valuable tool for mechanistic studies of gene function and disease modeling.展开更多
The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynam...The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynamic agents belong to distinct groups.Interactions are cooperative-antagonistic within each group and sign-in-degree balanced across the inter-groups.Firstly,a state feedback control protocol is designed to ensure that the trajectories of followers in diverse groups can converge to distinct convex hulls formed by their corresponding leaders,respectively.As an extension,the bipartite control problem with time-variant formation for the multi-agent system(MAS)is also considered,and a corresponding control protocol with formation compensation vectors is given.Finally,in view of Lyapunov stability theory and matrix inequality,the sufficient conditions for realizing the bipartite containment control are obtained,and several simulations are provided to verify the validity of the above methods.展开更多
Fault-tolerant systems are crucial for ensuring the reliability and availability of missioncritical applications in modern computing environments.The dynamic heterogeneous redundancy(DHR)architecture is a key componen...Fault-tolerant systems are crucial for ensuring the reliability and availability of missioncritical applications in modern computing environments.The dynamic heterogeneous redundancy(DHR)architecture is a key component in constructing fault-tolerant systems,particularly in areas such as national security,power networks,and banking private networks.DHR is transforming the cyberspace security industry chain by accommodating a broader range of applications and increasingly capturing the market.However,the development of applications for DHR architecture encounters challenges due to the complexities of handling heterogeneity,managing dynamism,and maintaining usability.To address these issues,we introduce MimicStudio,a comprehensive development framework with a standardized workflow.To our knowledge,MimicStudio is the first effective solution for DHR software development.We present a detailed implementation of MimicStudio with a heterogeneous microcontroller unit project,encompassing three CPUs with different instruction set architectures.The paper evaluates MimicStudio’s support for essential features,including zero-copy synchronization,parallelized build,multi-core collaborative debugging,and dynamic adjustment of the software system’s structure.Our results show that MimicStudio provides a flexible and efficient solution for supporting the dynamic,heterogeneous,and redundant features of fault-tolerant systems.展开更多
In this article,we show the existence,uniqueness and stability of bounded solutions to the following quasilinear problems with mean curvature operator(φ'(x′(t)))′=f(t,x),t≥t_(0),lim_(t→∞)x(t)=ψ_(0),lim_(t→...In this article,we show the existence,uniqueness and stability of bounded solutions to the following quasilinear problems with mean curvature operator(φ'(x′(t)))′=f(t,x),t≥t_(0),lim_(t→∞)x(t)=ψ_(0),lim_(t→∞)x′(t)e^(t)=0,where t_(0) and ψ_(0) are real constants,φ(s)=s/√1−s^(2),s∈R with s∈(−1,1),f:[t_(0),∞)×R→R satisfies the Lipschitz or Osgood-type conditions.展开更多
Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized ma...Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized management and transmission latency of the cloud makes it difficult to support real-time processing and distributed access structures.As a result,fog computing and the Internet of Things(IoT)have emerged as crucial applications.Fog-assisted proxy re-encryption is a commonly adopted technique for sharing cloud ciphertexts.It allows a semitrusted proxy to transforma data owner’s ciphertext into another re-encrypted ciphertext intended for a data requester,without compromising any information about the original ciphertext.Yet,the user revocation and cloud ciphertext renewal problems still lack effective and secure mechanisms.Motivated by it,we propose a revocable conditional proxy re-encryption scheme offering ciphertext evolution(R-CPRE-CE).In particular,a periodically updated time key is used to revoke the user’s access privileges while an access condition prevents a malicious proxy from reencrypting unauthorized ciphertext.We also demonstrate that our scheme is provably secure under the notion of indistinguishability against adaptively chosen identity and chosen ciphertext attacks in the random oracle model.Performance analysis shows that our scheme reduces the computation time for a complete data access cycle from an initial query to the final decryption by approximately 47.05%compared to related schemes.展开更多
The dynamic characteristics of the track system can directly affect its service performance and failure process.To explore the load characteristics and dynamic response of the track system under the dynamic loads from...The dynamic characteristics of the track system can directly affect its service performance and failure process.To explore the load characteristics and dynamic response of the track system under the dynamic loads from the rack vehicle in traction conditions,a systematic test of the track subsystem was carried out on a large-slope test line.In the test,the bending stress of the rack teeth,the wheel-rail forces,and the acceleration of crucial components in the track system were measured.Subsequently,a detailed analysis was conducted on the tested signals of the rack railway track system in the time domain and the time-frequency domains.The test results indicate that the traction force significantly affects the rack tooth bending stress and the wheel-rail forces.The vibrations of the track system under the traction conditions are mainly caused by the impacts generated from the gear-rack engagement,which are then transferred to the sleepers,the rails,and the ballast beds.Furthermore,both the maximum stress on the racks and the wheel-rail forces measured on the rails remain below their allowable values.This experimental study evaluates the load characteristics and reveals the vibration characteristics of the rack railway track system under the vehicle’s ultimate load,which is very important for the load-strengthening design of the key components such as racks and the vibration and noise reduction of the track system.展开更多
In this paper,we study the asymptotic behavior of the micropolar fluid flow through a thin domain,assuming zero Dirichlet boundary condition on the top boundary,which is rapidly oscillating,and non-standard boundary c...In this paper,we study the asymptotic behavior of the micropolar fluid flow through a thin domain,assuming zero Dirichlet boundary condition on the top boundary,which is rapidly oscillating,and non-standard boundary conditions on the flat bottom.Assuming“Reynolds roughness regime”,in which the thickness of the domain is very small compared to the wavelength of the roughness(i.e.a very slight roughness),we rigorously derive a generalized Reynolds equation for pressure,clearly showing the roughness-induced effects.Moreover,we give expressions for the average velocity and microrotation.展开更多
Under equivalent stiffness conditions,material substitution based on a thin-walled design is crucial for the lightweight of components.Developing high-performance steels with both high-yield strength and excellent duc...Under equivalent stiffness conditions,material substitution based on a thin-walled design is crucial for the lightweight of components.Developing high-performance steels with both high-yield strength and excellent ductility has become a key focus in fields like aerospace and lowaltitude flight.The novel low-density steel presented here exhibits a yield strength of 1000 MPa,which is 2-3 times higher than conventional low-alloy high-strength steels,while maintaining an elongation of about 18.7%.By combining ex-situ experimental characterization with a phase mechanical response model based on the iso-work theory and the von Mises equivalent method,the role of heterogeneous deformation-induced strengthening was revealed.The calculated values align closely with experimental results.This exceptional performance is attributed to a multiphase heterogeneous microstructure,where fresh martensite,bainite/tempered martensite,and deformation-induced martensite act as hard regions.These regions release micro-stresses through inhomogeneous cooperative deformation with soft ferrite,enabling multiple plastic deformation mechanisms and stress concentration relief.This research offers new insights into optimizing microstructures through mechanical metallurgy,which is crucial for producing high-performance,lightweight components.展开更多
The main purpose of using geothermal energy piles(GEPs)is to enable the exploitation of geothermal energy for meeting the heating/cooling demands of buildings efficiently.However,the installation process of convention...The main purpose of using geothermal energy piles(GEPs)is to enable the exploitation of geothermal energy for meeting the heating/cooling demands of buildings efficiently.However,the installation process of conventional GEPs is inconvenient compared with that of traditional foundation piles.The pre-bored grouted planted geothermal energy pile(PGP GEP)is an innovative technology to simplify the installation process.Most investigations of in-situ experiments for conventional GEPs have focused on summer conditions.An in-situ test for a PGP GEP was conducted to analyze the temperature changes and thermo-mechanical characteristics under winter conditions.The results show that the average temperature of the pile decreased by 5.1℃,and the pile exhibited a general trend of high temperatures at both ends and low temperatures in the middle.In mechanics,strong pile end restraints resulted in smaller observed axial strain and higher axial thermal-induced force in the pile ends than at the middle of the pile.展开更多
基金supported by the Chung-Ang University Research Grants in 2023.Alsothe work is supported by the ELLIIT Excellence Center at Linköping–Lund in Information Technology in Sweden.
文摘Recommending personalized travel routes from sparse,implicit feedback poses a significant challenge,as conventional systems often struggle with information overload and fail to capture the complex,sequential nature of user preferences.To address this,we propose a Conditional Generative Adversarial Network(CGAN)that generates diverse and highly relevant itineraries.Our approach begins by constructing a conditional vector that encapsulates a user’s profile.This vector uniquely fuses embeddings from a Heterogeneous Information Network(HIN)to model complex user-place-route relationships,a Recurrent Neural Network(RNN)to capture sequential path dynamics,and Neural Collaborative Filtering(NCF)to incorporate collaborative signals from the wider user base.This comprehensive condition,further enhanced with features representing user interaction confidence and uncertainty,steers a CGAN stabilized by spectral normalization to generate high-fidelity latent route representations,effectively mitigating the data sparsity problem.Recommendations are then formulated using an Anchor-and-Expand algorithm,which selects relevant starting Points of Interest(POI)based on user history,then expands routes through latent similarity matching and geographic coherence optimization,culminating in Traveling Salesman Problem(TSP)-based route optimization for practical travel distances.Experiments on a real-world check-in dataset validate our model’s unique generative capability,achieving F1 scores ranging from 0.163 to 0.305,and near-zero pairs−F1 scores between 0.002 and 0.022.These results confirm the model’s success in generating novel travel routes by recommending new locations and sequences rather than replicating users’past itineraries.This work provides a robust solution for personalized travel planning,capable of generating novel and compelling routes for both new and existing users by learning from collective travel intelligence.
基金supported by the Key Project of Science and Technology Research by Chongqing Education Commission under Grant KJZD-K202400610the Chongqing Natural Science Foundation General Project Grant CSTB2025NSCQ-GPX1263.
文摘The ubiquitous adoption of mobile devices as essential platforms for sensitive data transmission has heightened the demand for secure client-server communication.Although various authentication and key agreement protocols have been developed,current approaches are constrained by homogeneous cryptosystem frameworks,namely public key infrastructure(PKI),identity-based cryptography(IBC),or certificateless cryptography(CLC),each presenting limitations in client-server architectures.Specifically,PKI incurs certificate management overhead,IBC introduces key escrow risks,and CLC encounters cross-system interoperability challenges.To overcome these shortcomings,this study introduces a heterogeneous signcryption-based authentication and key agreement protocol that synergistically integrates IBC for client operations(eliminating PKI’s certificate dependency)with CLC for server implementation(mitigating IBC’s key escrow issue while preserving efficiency).Rigorous security analysis under the mBR(modified Bellare-Rogaway)model confirms the protocol’s resistance to adaptive chosen-ciphertext attacks.Quantitative comparisons demonstrate that the proposed protocol achieves 10.08%–71.34%lower communication overhead than existing schemes across multiple security levels(80-,112-,and 128-bit)compared to existing protocols.
基金supported by the National Natural Science Foundation of China(22074072,22274083,52376199)the Shandong Provincial Natural Science Foundation(ZR2023LZY005)+1 种基金the Exploration Project of the State Key Laboratory of BioFibers and EcoTextiles of Qingdao University(TSKT202101)the Fundamental Research Funds for the Central Universities(2022BLRD13,2023BLRD01).
文摘A rapidly growing field is piezoresistive sensor for accurate respiration rate monitoring to suppress the worldwide respiratory illness.However,a large neglected issue is the sensing durability and accuracy without interference since the expiratory pressure always coupled with external humidity and temperature variations,as well as mechanical motion artifacts.Herein,a robust and biodegradable piezoresistive sensor is reported that consists of heterogeneous MXene/cellulose-gelation sensing layer and Ag-based interdigital electrode,featuring customizable cylindrical interface arrangement and compact hierarchical laminated architecture for collectively regulating the piezoresistive response and mechanical robustness,thereby realizing the long-term breath-induced pressure detection.Notably,molecular dynamics simulations reveal the frequent angle inversion and reorientation of MXene/cellulose in vacuum filtration,driven by shear forces and interfacial interactions,which facilitate the establishment of hydrogen bonds and optimize the architecture design in sensing layer.The resultant sensor delivers unprecedented collection features of superior stability for off-axis deformation(0-120°,~2.8×10^(-3) A)and sensing accuracy without crosstalk(humidity 50%-100%and temperature 30-80).Besides,the sensor-embedded mask together with machine learning models is achieved to train and classify the respiration status for volunteers with different ages(average prediction accuracy~90%).It is envisioned that the customizable architecture design and sensor paradigm will shed light on the advanced stability of sustainable electronics and pave the way for the commercial application in respiratory monitory.
基金supported by the National Natural Science Foundation of China(No.52304358)Young Elite Scientists Sponsorship Program by CAST(No.YESS20230462).
文摘Heterogeneous nucleation,characterized by its low nucleation barrier and controllable nucleation sites,has been widely employed to manipulate the microstructures and properties of metallic materials.In recent years,the dispersion of inclusions,carbides,and microstructure refinement in steel have emerged as one of the key research directions in the development of high-quality steel.The current research status regarding the regulation of inclusions,carbides,and microstructures in steel through heterogeneous nucleation are reviewed.The key points and challenges in refining the second phase and microstructure in steel using inclusion particles are highlighted,aiming to provide inspiration and references for future scholars.Deoxidized inclusions,when refined and dispersed,exhibit favorable lattice matching with second phases(e.g.,nitrides,sulfides,carbides)in steel.This characteristic serves as the fundamental mechanism for achieving refinement of the second phase.Concurrently,the solid-solution alloying effect from deoxidizing metals contributes to second-phase refinement,an aspect that requires prioritized investigation.In addition to the single heterogeneous nucleation refinement effect,the two-stage heterogeneous nucleation refinement of the second phase and microstructure offers a new approach for follow-up research.Notably,second-phase particles added as heterogeneous nucleation sites via external addition often require surface modification to ensure their stable retention in steel at high temperatures,which remains a major challenge restricting the widespread application of this method.Currently,the explanation of heterogeneous nucleation phenomena primarily relies on empirical calculations of lattice mismatch between the substrate and the nucleating phase,which cannot fully elucidate the quantitative relationship on the interface between the substrate and the nucleation phase.On this basis,quantifying the electronic structure and nucleation barrier at the interface between the substrate and the nucleation phase is a critical direction worthy of increased attention in the future.
基金supported by the National Natural Science Foundation of China under Grant No.62162009the Key Technologies R&D Program of He’nan Province under Grant No.242102211065+2 种基金the Postgraduate Education Reform and Quality Improvement Project of Henan Province under Grant Nos.YJS2025GZZ36,YJS2024AL112,and YJS2024JD38the Innovation Scientists and Technicians Troop Construction Projects of Henan Province under Grant No.CXTD2017099the Scientific Research Innovation Team of Xuchang University under Grant No.2022CXTD003.
文摘With the increasing complexity of malware attack techniques,traditional detection methods face significant challenges,such as privacy preservation,data heterogeneity,and lacking category information.To address these issues,we propose Federated Dynamic Prototype Learning(FedDPL)for malware classification by integrating Federated Learning with a specifically designed K-means.Under the Federated Learning framework,model training occurs locally without data sharing,effectively protecting user data privacy and preventing the leakage of sensitive information.Furthermore,to tackle the challenges of data heterogeneity and the lack of category information,FedDPL introduces a dynamic prototype learning mechanism,which adaptively adjusts the clustering prototypes in terms of position and number.Thus,the dependency on predefined category numbers in typical K-means and its variants can be significantly reduced,resulting in improved clustering performance.Theoretically,it provides a more accurate detection of malicious behavior.Experimental results confirm that FedDPL excels in handling malware classification tasks,demonstrating superior accuracy,robustness,and privacy protection.
基金financially supported by the National Natural Science Foundation of China(No.52473338)the National Natural Science Foundation of China(Nos.52173004 and 51873055)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0540000)Advanced Materials-National Science and Technology Major Project(No.2025ZD0614000)Hebei Natural Science Foundation(No.E2022202015)Anhui Province Science and Technology Innovation Tackling Key Project(No.202423i08050025)。
文摘Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.
基金supported by the National Natural Science Foundation of China(22138004)Shaoxing Science and Technology Plan Project(2022B43001,2023B43001).
文摘To obtain protease-and lipase-producing halotolerant/halophilic strains suitable for shrimp paste(SP)fermentation,the microbial community structure and enzyme-producing microbial species were analyzed and predicted using metagenomics in 3 high-salt samples.Based on the linear salt gradient method,128 strains were screened.Eight halotolerant/halophilic strains highly producing 2 types of enzymes were identified and inoculated into lowsalt SP to assess the heterogeneity of SP.Physicochemical properties of SP indicated that Bacillus subtilis XJ-11,Virgibacillus halodenitrificans XJ-229,Piscibacillus halophilus XY-193,and Bacillus vallismortis HT-73 were more suitable for rapid fermentation of SP.Nutritional analysis showed that SP inoculated with V.halodenitrificans XJ-229 had the highest free amino acid content and SP inoculated with P.halophilus XY-193 had the highest unsaturated fatty acid content.The former had prominent umami,sweetness,and meaty aroma,weak bitterness and fishy flavor,and the closest flavor to the control(CP)based on sensory evaluation and E-nose analysis.A total of 61 volatile compounds were detected in all samples by SPME-GC-MS,of which 32,23,40,24,and 28 were detected in the CP and SP inoculated with B.subtilis XJ-11,V.halodenitrificans XJ-229,P.halophilus XY-193,and B.vallismortis HT-73,respectively,with 12,11,12,9,and 9 key flavor compounds.Among several samples,the highest levels of pyrazines,aldehydes,alcohols,and ketones were found in SP inoculated with B.subtilis XJ-11,V.halodenitrificans XJ-229,P.halophilus XY-193,and B.vallismortis HT-73,respectively.These results suggested that inoculation of different enzyme-producing halotolerant/halophilic strains resulted in differences in SP quality and main flavors.This study provides some references for process control and interpretation of heterogeneous mechanisms in low-salt SP fermented by inoculated strains.
基金supported by the National Key Laboratory of Helicopter Aeromechanics Fund(No.2024-CXPT-GF-JJ-093-05).
文摘The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration of rotorcraft.The aerodynamic interaction of tandem tilt-wing and multi-rotor is investigated based on the CFD method.The aerodynamic effect of multi tilt-rotor is simulated as virtual disk modeling by adding source terms to the Navier-Stokes equations,effectively reducing the calculation time while maintaining the accuracy of aerodynamic interaction calculations.Aerodynamic forces and flow field characteristics of the tandem tilt-wing and multi-rotor under different tilt angles are compared between cases with and without aerodynamic interaction.Furthermore,the differences in aerodynamic forces between dynamic tilt transition and fixed-angle conditions were compared.The results show that the aerodynamic interaction of multi-rotor obviously increases the lift of front tilt-wing at different tilt angles,the wing lift under interaction is increased by more than 40%compared with isolated wing at tilt angle of 15°for the computation in this paper,which is related to the increase of wing flow velocity and the suppression of flow separation caused by multi-rotor;the wing blocking effect will increase rotor thrust,especially near the tilt angles of 30°and 45°;the increases of rear wing lift and rear rotor thrust under aerodynamic interaction are not significant because of suppression by the front wing’s downwash;the unsteady effects during dynamic tilting have a relatively minor impact on aerodynamic interaction,with the aerodynamic forces on the rotors and wings during the dynamic tilting process showing little difference from those under corresponding fixed tilt angles.
基金supported by the National Natural Science Foundation of China(62463007,62463005)the Natural Science Foundation of Hainan Province(625RC710,625MS047)+1 种基金the System Control and Information Processing Education Ministry Key Laboratory Open Funding,China(Scip20240119)the Science Research Funding of Hainan University,China(KYQD(ZR)22180,KYQD(ZR)23180).
文摘This paper focuses on the leader-following positive consensus problems of heterogeneous switched multi-agent systems.First,a state-feedback controller with dynamic compensation is introduced to achieve positive consensus under average dwell time switching.Then sufficient conditions are derived to guarantee the positive consensus.The gain matrices of the control protocol are described using a matrix decomposition approach and the corresponding computational complexity is reduced by resorting to linear programming and co-positive Lyapunov functions.Finally,two numerical examples are provided to illustrate the results obtained.
基金supported by the National Natural Science Foundation of China(Grant No.62172033).
文摘Urban traffic generates massive and diverse data,yet most systems remain fragmented.Current approaches to congestion management suffer from weak data consistency and poor scalability.This study addresses this gap by proposing the Urban Traffic Congestion Unified Metadata Model(UTC-UMM).The goal is to provide a standardized and extensible framework for describing,extracting,and storing multisource traffic data in smart cities.The model defines a two-tier specification that organizes nine core traffic resource classes.It employs an eXtensible Markup Language(XML)Schema that connects general elements with resource-specific elements.This design ensures both syntactic and semantic interoperability across siloed datasets.Extension principles allow new elements or constraints to be introducedwithout breaking backward compatibility.Adistributed pipeline is implemented usingHadoop Distributed File System(HDFS)and HBase.It integrates computer vision for video and natural language processing for text to automate metadata extraction.Optimized row-key designs enable low-latency queries.Performance is tested with the Yahoo!Cloud Serving Benchmark(YCSB),which shows linear scalability and high throughput.The results demonstrate that UTC-UMM can unify heterogeneous traffic data while supporting real-time analytics.The discussion highlights its potential to improve data reuse,portability,and scalability in urban congestion studies.Future research will explore integration with association rulemining and advanced knowledge representation to capture richer spatiotemporal traffic patterns.
基金supported by the 2024 Research Fund of University of Ulsan.
文摘In recent years,three-dimensional reconstruction technologies that employ multiple cameras have continued to evolve significantly,enabling remote collaboration among users in extended Reality(XR)environments.In addition,methods for deploying multiple cameras for motion capture of users(e.g.,performers)are widely used in computer graphics.As the need to minimize and optimize the number of cameras grows to reduce costs,various technologies and research approaches focused on Optimal Camera Placement(OCP)are continually being proposed.However,as most existing studies assume homogeneous camera setups,there is a growing demand for studies on heterogeneous camera setups.For instance,technical demands keep emerging in scenarios with minimal camera configurations,especially regarding cost factors,the physical placement of cameras given the spatial structure,and image capture strategies for heterogeneous cameras,such as high-resolution RGB cameras and depth cameras.In this study,we propose a pre-visualization and simulation method for the optimal placement of heterogeneous cameras in XR environments,accounting for both the specifications of heterogeneous cameras(e.g.,field of view)and the physical configuration(e.g.,wall configuration)in real-world spaces.The proposed method performs a visibility analysis of cameras by considering each camera’s field-of-view volume,resolution,and unique characteristics,along with physicalspace constraints.This approach enables the optimal position and rotation of each camera to be recommended,along with the minimum number of cameras required.In the results of our study conducted in heterogeneous camera combinations,the proposed method achieved 81.7%~82.7%coverage of the target visual information using only 2~3 cameras.In contrast,single(or homogeneous)-typed cameras were required to use 11 cameras for 81.6%coverage.Accordingly,we found that camera deployment resources can be reduced with the proposed approaches.
基金State Key Laboratory Special Fund,Grant/Award Number:2060204Open Research Project in State Key Laboratory of Vascular Homeostasis and Remodeling,Grant/Award Number:Peking University,202411+3 种基金The Non-profit Central Research Institute Fund of the Chinese Academy of Medical Sciences,Grant/Award Number:2023-PT180-01Haihe Laboratory of Cell Ecosystem Innovation Fund,Grant/Award Number:HH24KYZX0007CAMS Innovation Fund for Medical Sciences,Grant/Award Number:2021-I2M-1-024,2022-I2M-1-020 and 2023-I2M-2-001the National Key Research and Development Program of China from the Ministry of Science and Technology,Grant/Award Number:2021YFF0702802。
文摘Background:The golden Syrian hamster is a valuable animal model for studying carcinogenesis,metabolic disorders,cardiovascular diseases,and viral infections due to its biological and pathological similarities to humans.However,the development of genetically engineered hamsters has lagged behind that of mice and rats,largely because of an embryonic development block at the two-cell stage in vitro.Although CRISPR/Cas9-mediated gene knockout has been achieved in hamsters,precise DNA fragment insertion or conditional knockout(cKO)models have not previously been reported,likely due to technical limitations in embryo manipulation and insufficient efficiency of homology-directed repair(HDR).Methods:In this study,we generated conditional alleles of the ApoF gene in golden Syrian hamsters.A two-cut strategy was applied using Cas9 protein,two sgRNAs,and a single donor plasmid containing exon 2 flanked by loxP sites and two~0.8 kb homology arms.A mixture of Cas9 protein,sgRNAs,and the donor plasmid was microinjected into the pronuclei of one-cell stage hamster embryos.Results:The efficiency of CRISPR/Cas9-mediated loxP knock-in reached up to 27%,and the genetically modified floxed alleles were successfully transmitted through the germline.The functionality of the inserted loxP sites was validated by in vivo Cremediated recombination following local administration of AAV vectors,including AAV-cTnT-Cre in the heart and AAV-CMV-Cre in the brain.Conclusions:To our knowledge,this work represents the first successful establishment of a conditional knockout model in the golden Syrian hamster,providing a valuable tool for mechanistic studies of gene function and disease modeling.
基金National Natural Science Foundation of China(No.12071370)。
文摘The bipartite containment control problem for heterogeneous nonlinear multi-agent systems(HNMASs)within multi-group networks under signed digraphs is investigated,where the first-order and second-order nonlinear dynamic agents belong to distinct groups.Interactions are cooperative-antagonistic within each group and sign-in-degree balanced across the inter-groups.Firstly,a state feedback control protocol is designed to ensure that the trajectories of followers in diverse groups can converge to distinct convex hulls formed by their corresponding leaders,respectively.As an extension,the bipartite control problem with time-variant formation for the multi-agent system(MAS)is also considered,and a corresponding control protocol with formation compensation vectors is given.Finally,in view of Lyapunov stability theory and matrix inequality,the sufficient conditions for realizing the bipartite containment control are obtained,and several simulations are provided to verify the validity of the above methods.
基金supported by National Key Research and Development Program of China(No.2023YFB 4404200).
文摘Fault-tolerant systems are crucial for ensuring the reliability and availability of missioncritical applications in modern computing environments.The dynamic heterogeneous redundancy(DHR)architecture is a key component in constructing fault-tolerant systems,particularly in areas such as national security,power networks,and banking private networks.DHR is transforming the cyberspace security industry chain by accommodating a broader range of applications and increasingly capturing the market.However,the development of applications for DHR architecture encounters challenges due to the complexities of handling heterogeneity,managing dynamism,and maintaining usability.To address these issues,we introduce MimicStudio,a comprehensive development framework with a standardized workflow.To our knowledge,MimicStudio is the first effective solution for DHR software development.We present a detailed implementation of MimicStudio with a heterogeneous microcontroller unit project,encompassing three CPUs with different instruction set architectures.The paper evaluates MimicStudio’s support for essential features,including zero-copy synchronization,parallelized build,multi-core collaborative debugging,and dynamic adjustment of the software system’s structure.Our results show that MimicStudio provides a flexible and efficient solution for supporting the dynamic,heterogeneous,and redundant features of fault-tolerant systems.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12361040,12061064)the National Science Foundation of Gansu Province(Grant No.22JR5RA264)State Scholarship Fund(Grant No.20230862021).
文摘In this article,we show the existence,uniqueness and stability of bounded solutions to the following quasilinear problems with mean curvature operator(φ'(x′(t)))′=f(t,x),t≥t_(0),lim_(t→∞)x(t)=ψ_(0),lim_(t→∞)x′(t)e^(t)=0,where t_(0) and ψ_(0) are real constants,φ(s)=s/√1−s^(2),s∈R with s∈(−1,1),f:[t_(0),∞)×R→R satisfies the Lipschitz or Osgood-type conditions.
基金supported in part by the National Science and Technology Council of Republic of China under the contract numbers NSTC 114-2221-E-019-055-MY2NSTC 114-2221-E-019-069.
文摘Cloud data sharing is an important issue in modern times.To maintain the privacy and confidentiality of data stored in the cloud,encryption is an inevitable process before uploading the data.However,the centralized management and transmission latency of the cloud makes it difficult to support real-time processing and distributed access structures.As a result,fog computing and the Internet of Things(IoT)have emerged as crucial applications.Fog-assisted proxy re-encryption is a commonly adopted technique for sharing cloud ciphertexts.It allows a semitrusted proxy to transforma data owner’s ciphertext into another re-encrypted ciphertext intended for a data requester,without compromising any information about the original ciphertext.Yet,the user revocation and cloud ciphertext renewal problems still lack effective and secure mechanisms.Motivated by it,we propose a revocable conditional proxy re-encryption scheme offering ciphertext evolution(R-CPRE-CE).In particular,a periodically updated time key is used to revoke the user’s access privileges while an access condition prevents a malicious proxy from reencrypting unauthorized ciphertext.We also demonstrate that our scheme is provably secure under the notion of indistinguishability against adaptively chosen identity and chosen ciphertext attacks in the random oracle model.Performance analysis shows that our scheme reduces the computation time for a complete data access cycle from an initial query to the final decryption by approximately 47.05%compared to related schemes.
基金supported by the National Natural Science Foundation of China(No.52388102)the Sichuan Science and Technology Program(No.2024NSFTD0011)the Fundamental Research Funds for the State Key Laboratory of Rail Transit Vehicle System of Southwest Jiaotong University(No.2023TPL-T11).
文摘The dynamic characteristics of the track system can directly affect its service performance and failure process.To explore the load characteristics and dynamic response of the track system under the dynamic loads from the rack vehicle in traction conditions,a systematic test of the track subsystem was carried out on a large-slope test line.In the test,the bending stress of the rack teeth,the wheel-rail forces,and the acceleration of crucial components in the track system were measured.Subsequently,a detailed analysis was conducted on the tested signals of the rack railway track system in the time domain and the time-frequency domains.The test results indicate that the traction force significantly affects the rack tooth bending stress and the wheel-rail forces.The vibrations of the track system under the traction conditions are mainly caused by the impacts generated from the gear-rack engagement,which are then transferred to the sleepers,the rails,and the ballast beds.Furthermore,both the maximum stress on the racks and the wheel-rail forces measured on the rails remain below their allowable values.This experimental study evaluates the load characteristics and reveals the vibration characteristics of the rack railway track system under the vehicle’s ultimate load,which is very important for the load-strengthening design of the key components such as racks and the vibration and noise reduction of the track system.
文摘In this paper,we study the asymptotic behavior of the micropolar fluid flow through a thin domain,assuming zero Dirichlet boundary condition on the top boundary,which is rapidly oscillating,and non-standard boundary conditions on the flat bottom.Assuming“Reynolds roughness regime”,in which the thickness of the domain is very small compared to the wavelength of the roughness(i.e.a very slight roughness),we rigorously derive a generalized Reynolds equation for pressure,clearly showing the roughness-induced effects.Moreover,we give expressions for the average velocity and microrotation.
基金funded by the National Natural Science Foundation of China(No.51974134)the Innovation Ability Promotion Plan Project of Hebei Province,China(No.24461002D)。
文摘Under equivalent stiffness conditions,material substitution based on a thin-walled design is crucial for the lightweight of components.Developing high-performance steels with both high-yield strength and excellent ductility has become a key focus in fields like aerospace and lowaltitude flight.The novel low-density steel presented here exhibits a yield strength of 1000 MPa,which is 2-3 times higher than conventional low-alloy high-strength steels,while maintaining an elongation of about 18.7%.By combining ex-situ experimental characterization with a phase mechanical response model based on the iso-work theory and the von Mises equivalent method,the role of heterogeneous deformation-induced strengthening was revealed.The calculated values align closely with experimental results.This exceptional performance is attributed to a multiphase heterogeneous microstructure,where fresh martensite,bainite/tempered martensite,and deformation-induced martensite act as hard regions.These regions release micro-stresses through inhomogeneous cooperative deformation with soft ferrite,enabling multiple plastic deformation mechanisms and stress concentration relief.This research offers new insights into optimizing microstructures through mechanical metallurgy,which is crucial for producing high-performance,lightweight components.
文摘The main purpose of using geothermal energy piles(GEPs)is to enable the exploitation of geothermal energy for meeting the heating/cooling demands of buildings efficiently.However,the installation process of conventional GEPs is inconvenient compared with that of traditional foundation piles.The pre-bored grouted planted geothermal energy pile(PGP GEP)is an innovative technology to simplify the installation process.Most investigations of in-situ experiments for conventional GEPs have focused on summer conditions.An in-situ test for a PGP GEP was conducted to analyze the temperature changes and thermo-mechanical characteristics under winter conditions.The results show that the average temperature of the pile decreased by 5.1℃,and the pile exhibited a general trend of high temperatures at both ends and low temperatures in the middle.In mechanics,strong pile end restraints resulted in smaller observed axial strain and higher axial thermal-induced force in the pile ends than at the middle of the pile.
