Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into...Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into the new β phase during the pulsed current-assisted aging process,and then the newly formed β phase is mainly transformed into the β_(t) phase,with occasional transition to new α_(p) phase,leading to a remarkable grain refinement,especially for the lamellarαs phases.In comparison to conventional aging treatment,the pulsed current-assisted aging approach achieves a significant enhancement in strength without degrading ductility,yielding an excellent mechanical property combination:a yield strength of 932 MPa,a tensile strength of 1042 MPa,and an elongation of 12.2%.It is primarily ascribed to the increased fraction of β_(t) phases,the obvious grain refinement effect,and the slip block effect induced by the multiple-variantαs colonies distributed within β_(t) phases.展开更多
Joining dissimilar materials encounters significant engineering challenges due to the contrast in material properties that makes conventional welding not feasible.Magnetic Pulse Welding(MPW)offers a solidstate joining...Joining dissimilar materials encounters significant engineering challenges due to the contrast in material properties that makes conventional welding not feasible.Magnetic Pulse Welding(MPW)offers a solidstate joining technique that overcomes these issues by using impact to create strong bonds without melting the substrate materials.This study investigates the weldability of aluminum alloy Al-5754 with Al-7075 and MARS 380 steel,used in armouring solutions of defense systems,by the use of MPW.In this work,weldability windows are investigated by varying standoff distances between the coating material and its substrate(0.25-4.5 mm)and discharge energies(5-13 kJ)with both O-shape and U-shape inductors.Mechanical strength of the welded joints were assessed through single lap shear tests,identifying optimal welding parameters.Then,the velocity profiles of the flyer plates were measured using heterodyne velocimetry to understand the dynamics of the impact.Then,substructures assembled with the optimal welding conditions were subjected to ballistic testing using 7.62 mm×51 mm NATO and 9 mm×19 mm Parabellum munitions to evaluate the resilience of the welds under ballistic impact.The outcomes demonstrate that MPW effectively joins Al-5754 with both Al-7075 and MARS 380,producing robust welds capable of withstanding ballistic impacts under certain conditions.This research advances the application of MPW in lightweight ballistic protection of defense systems,contributing to the development of more resilient and lighter protective structures.展开更多
Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V...Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V composites with superior strength and ductility is reported.展开更多
In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh enviro...In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh environment leads to significant variations in the shape and size of the defects.To address this challenge,we propose the multivariate time series segmentation network(MSSN),which adopts a multiscale convolutional network with multi-stage and depth-separable convolutions for efficient feature extraction through variable-length templates.To tackle the classification difficulty caused by structural signal variance,MSSN employs logarithmic normalization to adjust instance distributions.Furthermore,it integrates classification with smoothing loss functions to accurately identify defect segments amid similar structural and defect signal subsequences.Our algorithm evaluated on both the Mackey-Glass dataset and industrial dataset achieves over 95%localization and demonstrates the capture capability on the synthetic dataset.In a nuclear plant's heat transfer tube dataset,it captures 90%of defect instances with75%middle localization F1 score.展开更多
BACKGROUND Human immunodeficiency virus(HIV)recency testing provides data that can be used to monitor the trend of new HIV infections.The effectiveness of using people identified with recent infection to identify part...BACKGROUND Human immunodeficiency virus(HIV)recency testing provides data that can be used to monitor the trend of new HIV infections.The effectiveness of using people identified with recent infection to identify partners with new HIV infection through partner notification services(PNS)is not well documented.AIM To determine the pooled prevalence of recency testing coverage,recent infection,reclassification(recent to longterm infection)and PNS cascade among newly diagnosed people living with HIV.METHODS PubMed,Cochrane Library and Embase were searched for articles published between January 2018 and November 2024.Studies were included if they reported recency coverage and/or PNS among people newly diagnosed with HIV and used recent infection testing algorithm(RITA).Recency coverage was defined as proportion of people tested using rapid testing for recent infection(RTRI)among those newly diagnosed with HIV.RITA further classifies RTRI results using viral load results(≥1000 copies/mL vs<1000 copies/mL)to confirm recency status.For studies with PNS,we evaluated the cascade:Number of partners elicited,successfully contacted,eligible for HIV testing,tested and HIV diagnosis.PNS effectiveness was measured by proportion of new HIV diagnoses from tested partners.Using random effects models,we computed the pooled estimate of recency outcomes and 95%confidence intervals(CIs).RESULTS Twenty-five studies from 17-low-and middle-income countries were included.Of 276315 newly diagnosed people living with HIV,79864 underwent RTRI with an overall pooled recency coverage of 87%(95%CI:67-96).The pooled prevalence of RTRI and RITA recency were 12%(95%CI:9-16)and 7%(95%CI:4-10),respectively.Pooled prevalence of RTRI reclassification was 34%(95%CI:22-49).Of the recent cases who agreed to PNS,253 partners were elicited with an estimated elicitation ratio of 1:1.6.Among partners elicited,99%were successfully contacted,75%were eligible for testing,68%tested for HIV,and 15%were diagnosed with HIV.CONCLUSION High recency testing coverage among newly diagnosed individuals demonstrates the feasibility of monitoring new HIV infections in LMIC.While PNS yielded moderate HIV diagnoses,its targeted approach remains a critical strategy for identifying undiagnosed cases.展开更多
The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo ext...The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo extensive in-house tests and prolonged field tests for certification and approval before operational deployment,leading to high costs,delays,and operational disruptions.This paper introduces a GNSS-based train control localization framework which eliminates the need for on-site testing by leveraging train movement dynamics and 3D environment modeling to create a zero on-site testing platform.The proposed framework simulates train movement and the surrounding 3D environment using collected railway line location data and environmental attributes to generate realistic multipath signals and obscuration effects.This approach enables comprehensive laboratory-based case studies for train localization,reducing the huge amount test of needed for physical field trials.The framework is established in house,using the data collected at the Test Base of China Academy of Railway Sciences(Circular Railway).Results from the open area and cutting environment tests demonstrate high localization accuracy repeatability within the simulated environment,validating the feasibility and effectiveness of zero on-site testing for GNSS-based train control systems.This research highlights the potential of GNSS simulation platforms in enhancing cost efficiency,operational safety,and accuracy for future digital railways.展开更多
Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering impleme...Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.展开更多
1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-...1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.展开更多
A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped C...A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped CrCoNi MEAs at similar yield strength levels.P segregation at grain boundaries(GBs)and dissolution inside grain interiors,together with the related lower stacking fault energy(SFE)are found in the P-doped CrCoNi MEA.Higher hetero-deformation-induced(HDI)hardening rate is observed in the P-doped CrCoNi MEA due to the grain-to-grain plastic deformation and the dynamic structural refinement by high-density stacking fault-walls(SFWs).The enhanced yield strength in the P-doped CoCrNi MEA can be attributed to the strong substitutional solid-solution strengthening by severer lattice distortion and the GB strengthening by phosphorus segregation at GBs.During the tensile deformation,the multiple SFW frames inundated with massive multi-orientational tiny planar stacking faults(SFs)between them,rather than deformation twins,are observed to induce dynamic structural refinement for forming par-allelepiped domains in the P-doped CoCrNi MEA,due to the lower SFE and even lower atomically-local SFE.These nano-sized domains with domain boundary spacing at tens of nanometers can block disloca-tion movement for strengthening on one hand,and can accumulate defects in the interiors of domains for exceptionally high hardening rate on the other hand.展开更多
The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (...The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.展开更多
The rapid progress in the construction of heavy-haul and high-speed railways has led to a surge in rail defects and unforeseen failures.Addressing this issue necessitates the implementation of more sophisticated rail ...The rapid progress in the construction of heavy-haul and high-speed railways has led to a surge in rail defects and unforeseen failures.Addressing this issue necessitates the implementation of more sophisticated rail inspection methods,specifically involving real-time,precise detection,and assessment of rail defects.Current applications fail to address the evolving requirements,prompting the need for advancements.This paper provides a summary of various types of rail defects and outlines both traditional and innovative non-destructive inspection techniques,examining their fundamental features,benefits,drawbacks,and practical suitability for railway track inspection.It also explores potential enhancements to equipment and software.The comprehensive review draws upon pertinent international research and review papers.Furthermore,the paper introduces a fusion of inspection methods aimed at enhancing the overall reliability of defect detection.展开更多
The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analys...The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analysis of bridge inspection materials,the principle of ultrasonic non-destructive testing technology and its adaptability to bridge engineering are elaborated.Subsequently,starting from the preparation work before inspection until damage assessment,the entire process of ultrasonic non-destructive testing is studied,and finally,a technical system of ultrasonic non-destructive testing for bridge engineering that runs through the entire process is formed.It is hoped that this article can provide technical reference value for relevant units in China,and promote the high-quality development of China’s bridge engineering from a macro perspective.展开更多
With the depletion of fossil fuels and increasing environmental concerns,the development of renewable energy,such as wave energy,has become a critical component of global energy strategies.However,challenges persist i...With the depletion of fossil fuels and increasing environmental concerns,the development of renewable energy,such as wave energy,has become a critical component of global energy strategies.However,challenges persist in the field testing methodologies for wave energy converters(WECs).In this paper,a numerical wave field of the Dawanshan Island Sea Area in Zhuhai City is constructed based on the MIKE21 SW wave model and by using an NCEP wind field driving model.In conjunction with the IEC-62600-100 standard,by taking site testing of the“Wanshan”wave energy converter on which a sea trial has been conducted in Dawanshan Island of Zhuhai city as an example,research on-site testing method for a wave energy converter has been carried out.The wave measurement position for the“Wanshan”converter was determined by combining statistically analyzed field data with a validated numerical wave model.By comparing a valid wave height at the position where a wave rider is located with a valid wave height at the position where the“Wanshan”wave energy converter is situated,the correlation coefficient between simulation and observed data reached 0.90,with a root-mean-square error of 0.19.The representativeness of wave measurement data during site testing is verified and can be used as a basis for calculating the input energy of the“Wanshan”wave energy converter.展开更多
To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the ste...To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.展开更多
Subgrade engineering is a fundamental aspect of infrastructure construction in China.As the primary structural element responsible for bearing and distributing traffic loads,the subgrade must not only withstand the su...Subgrade engineering is a fundamental aspect of infrastructure construction in China.As the primary structural element responsible for bearing and distributing traffic loads,the subgrade must not only withstand the substantial pressures exerted by vehicles,trains,and other forms of transportation,but also efficiently transfer these loads to the underlying foundation,ensuring the stability and longevity of the roadway.In recent years,advancements in subgrade engineering technology have propelled the industry towards smarter,greener,and more sustainable practices,particularly in the areas of intelligent monitoring,disaster management,and innovative construction methods.This paper reviews the application and methodologies of intelligent testing equipment,including cone penetration testing(CPT)devices,soil resistivity testers,and intelligent rebound testers,in subgrade engineering.It examines the operating principles,advantages,limitations,and application ranges of these tools in subgrade testing.Additionally,the paper evaluates the practical use of advanced equipment from both domestic and international perspectives,addressing the challenges encountered by various instruments in realworld applications.These devices enable precise,comprehensive testing and evaluation of subgrade conditions at different stages,providing real-time data analysis and intelligent early warnings.This supports effective subgrade health management and maintenance.As intelligent technologies continue to evolve and integrate,these tools will increasingly enhance the accuracy,efficiency,and sustainability of subgrade monitoring.展开更多
Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by...Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by using portable diagnostic devices,avoiding sending samples to the medical laboratories.It has been extensively explored for diagnosing and monitoring patients’diseases and health conditions with the assistance of development in biochemistry and microfluidics.Microfluidic paper-based analytical devices(μPADs)have gained dramatic popularity in POCT because of their simplicity,user-friendly,fast and accurate result reading and low cost.SeveralμPADs have been successfully commercialized and received excellent feedback during the past several decades.This review briefly discusses the main types ofμPADs,preparation methods and their detection principles,followed by a few representative examples.The future perspectives of the development inμPADs are also provided.展开更多
Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 7...Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.展开更多
A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and prom...A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and promoting the precipitation of(Ti,Zr)_(6)Si_(3) silicides and theα2 phase.展开更多
Penetration testing plays a critical role in ensuring security in an increasingly interconnected world. Despite advancements in technology leading to smaller, more portable devices, penetration testing remains reliant...Penetration testing plays a critical role in ensuring security in an increasingly interconnected world. Despite advancements in technology leading to smaller, more portable devices, penetration testing remains reliant on traditional laptops and computers, which, while portable, lack true ultra-portability. This paper explores the potential impact of developing a dedicated, ultra-portable, low-cost device for on-the-go penetration testing. Such a device could replicate the core functionalities of advanced penetration testing tools, including those found in Kali Linux, within a compact form factor that fits easily into a pocket. By offering the convenience and portability akin to a smartphone, this innovative device could redefine the way penetration testers operate, enabling them to carry essential tools wherever they go and ensuring they are always prepared to conduct security assessments efficiently. This approach aims to revolutionize penetration testing by merging high functionality with unparalleled portability.展开更多
In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd...In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd-0.5Mn alloy,quasi-in-situ electron backscattered diffraction and two-beam diffraction were conducted.The results reveal that the Mg-Gd-Mn alloy exhibits a distinct rare-earth texture,and the activation of non-basal slip systems is evident from the clear observation of non-basal slip traces during the later stages of deformation.However,the primary deformation mechanisms in Mg-Gd-Mn alloy remain basalslip and{10–12}tensile twinning,and the remarkable ductility observed in Mg-Gd-Mn alloys can be attributed to the softening of non-basal slip modes,which leads to a coordinated deformation between various modes of deformation.To further validate this conclusion,an analysis was conducted using a visco-plastic self-consistent(VPSC)model to investigate the relative activity of basal and non-basal slip in Mg-Gd-Mn alloys.The obtained results align well with experimental observations,providing additional support for the hypothesis.展开更多
基金National Key Research and Development Program of China(2021YFB3700801)。
文摘Low-density short-duration pulsed current-assisted aging treatment was applied to the Ti-6Al-4V-0.5Mo-0.5Zr alloy subjected to different solution treatments.The results show that numerous α_(p) phases redissolve into the new β phase during the pulsed current-assisted aging process,and then the newly formed β phase is mainly transformed into the β_(t) phase,with occasional transition to new α_(p) phase,leading to a remarkable grain refinement,especially for the lamellarαs phases.In comparison to conventional aging treatment,the pulsed current-assisted aging approach achieves a significant enhancement in strength without degrading ductility,yielding an excellent mechanical property combination:a yield strength of 932 MPa,a tensile strength of 1042 MPa,and an elongation of 12.2%.It is primarily ascribed to the increased fraction of β_(t) phases,the obvious grain refinement effect,and the slip block effect induced by the multiple-variantαs colonies distributed within β_(t) phases.
基金funded on the one hand by Agence de l'Innovation de Défense(AID)grant reference number 2021650044on the other hand by Ecole Centrale de Nantes。
文摘Joining dissimilar materials encounters significant engineering challenges due to the contrast in material properties that makes conventional welding not feasible.Magnetic Pulse Welding(MPW)offers a solidstate joining technique that overcomes these issues by using impact to create strong bonds without melting the substrate materials.This study investigates the weldability of aluminum alloy Al-5754 with Al-7075 and MARS 380 steel,used in armouring solutions of defense systems,by the use of MPW.In this work,weldability windows are investigated by varying standoff distances between the coating material and its substrate(0.25-4.5 mm)and discharge energies(5-13 kJ)with both O-shape and U-shape inductors.Mechanical strength of the welded joints were assessed through single lap shear tests,identifying optimal welding parameters.Then,the velocity profiles of the flyer plates were measured using heterodyne velocimetry to understand the dynamics of the impact.Then,substructures assembled with the optimal welding conditions were subjected to ballistic testing using 7.62 mm×51 mm NATO and 9 mm×19 mm Parabellum munitions to evaluate the resilience of the welds under ballistic impact.The outcomes demonstrate that MPW effectively joins Al-5754 with both Al-7075 and MARS 380,producing robust welds capable of withstanding ballistic impacts under certain conditions.This research advances the application of MPW in lightweight ballistic protection of defense systems,contributing to the development of more resilient and lighter protective structures.
基金supported by the National Natural Science Foundation of China(NSFC,No.52271138)the Key Research and Development Projects of Shaanxi Province(Nos.2023-YBGY-433 and 2024GX-YBXM-356)+1 种基金Xi'an Talent Program Young Innovative Talents(No.XAYC 2023030)the Science and Technology Development Plan Project of Shaanxi Province(No.S2024-JC-QN-2642).
文摘Synergistically and simultaneously enhancing strength and ductility has been a major challenge for the development and applications of titanium matrix composites.Herein,a new design methodology for Ti_(2)Cu/Ti_(6)Al4V composites with superior strength and ductility is reported.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(2024ZD0608100)the National Natural Science Foundation of China(62332017,U22A2022)
文摘In high-risk industrial environments like nuclear power plants,precise defect identification and localization are essential for maintaining production stability and safety.However,the complexity of such a harsh environment leads to significant variations in the shape and size of the defects.To address this challenge,we propose the multivariate time series segmentation network(MSSN),which adopts a multiscale convolutional network with multi-stage and depth-separable convolutions for efficient feature extraction through variable-length templates.To tackle the classification difficulty caused by structural signal variance,MSSN employs logarithmic normalization to adjust instance distributions.Furthermore,it integrates classification with smoothing loss functions to accurately identify defect segments amid similar structural and defect signal subsequences.Our algorithm evaluated on both the Mackey-Glass dataset and industrial dataset achieves over 95%localization and demonstrates the capture capability on the synthetic dataset.In a nuclear plant's heat transfer tube dataset,it captures 90%of defect instances with75%middle localization F1 score.
文摘BACKGROUND Human immunodeficiency virus(HIV)recency testing provides data that can be used to monitor the trend of new HIV infections.The effectiveness of using people identified with recent infection to identify partners with new HIV infection through partner notification services(PNS)is not well documented.AIM To determine the pooled prevalence of recency testing coverage,recent infection,reclassification(recent to longterm infection)and PNS cascade among newly diagnosed people living with HIV.METHODS PubMed,Cochrane Library and Embase were searched for articles published between January 2018 and November 2024.Studies were included if they reported recency coverage and/or PNS among people newly diagnosed with HIV and used recent infection testing algorithm(RITA).Recency coverage was defined as proportion of people tested using rapid testing for recent infection(RTRI)among those newly diagnosed with HIV.RITA further classifies RTRI results using viral load results(≥1000 copies/mL vs<1000 copies/mL)to confirm recency status.For studies with PNS,we evaluated the cascade:Number of partners elicited,successfully contacted,eligible for HIV testing,tested and HIV diagnosis.PNS effectiveness was measured by proportion of new HIV diagnoses from tested partners.Using random effects models,we computed the pooled estimate of recency outcomes and 95%confidence intervals(CIs).RESULTS Twenty-five studies from 17-low-and middle-income countries were included.Of 276315 newly diagnosed people living with HIV,79864 underwent RTRI with an overall pooled recency coverage of 87%(95%CI:67-96).The pooled prevalence of RTRI and RITA recency were 12%(95%CI:9-16)and 7%(95%CI:4-10),respectively.Pooled prevalence of RTRI reclassification was 34%(95%CI:22-49).Of the recent cases who agreed to PNS,253 partners were elicited with an estimated elicitation ratio of 1:1.6.Among partners elicited,99%were successfully contacted,75%were eligible for testing,68%tested for HIV,and 15%were diagnosed with HIV.CONCLUSION High recency testing coverage among newly diagnosed individuals demonstrates the feasibility of monitoring new HIV infections in LMIC.While PNS yielded moderate HIV diagnoses,its targeted approach remains a critical strategy for identifying undiagnosed cases.
基金supported by the National Natural Science Foundation of China(62027809,U2268206,T2222015,U2468202).
文摘The integration of Global Navigation Satellite System(GNSS)technology into railway train control systems is a crucial step toward achieving the vision of a digital railway.Traditional train control systems undergo extensive in-house tests and prolonged field tests for certification and approval before operational deployment,leading to high costs,delays,and operational disruptions.This paper introduces a GNSS-based train control localization framework which eliminates the need for on-site testing by leveraging train movement dynamics and 3D environment modeling to create a zero on-site testing platform.The proposed framework simulates train movement and the surrounding 3D environment using collected railway line location data and environmental attributes to generate realistic multipath signals and obscuration effects.This approach enables comprehensive laboratory-based case studies for train localization,reducing the huge amount test of needed for physical field trials.The framework is established in house,using the data collected at the Test Base of China Academy of Railway Sciences(Circular Railway).Results from the open area and cutting environment tests demonstrate high localization accuracy repeatability within the simulated environment,validating the feasibility and effectiveness of zero on-site testing for GNSS-based train control systems.This research highlights the potential of GNSS simulation platforms in enhancing cost efficiency,operational safety,and accuracy for future digital railways.
基金supported by the National Natural Science Foundation of China(Nos.51925103,52271149,52171159)the Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-09-E00114)+5 种基金the Natural Science Foundation of Shanghai(22ZR1422500)the Innovation Program of Shanghai Science and Technology(No.23520760700)the Aviation Foundation(No.2023Z0530S6004)the Fund of the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP202221)the financial support from Program 173(No.2020-JCIQ-ZD-186-01)the Space Utilization System of China Manned Space Engineering(No.KJZ-YY-NCL08).
文摘Lightweight high/medium-entropy alloys(H/MEAs)possess attractive properties such as high strength-to-weight ratios,however,their limited room-temperature tensile ductility hinders their widespread engi-neering implementation,for instance in aerospace structural components.This work achieved a transfor-mative improvement of room-temperature tensile ductility in Ti-V-Zr-Nb MEAs with densities of 5.4-6.5 g/cm3,via ingenious composition modulation.Through the systematic co-adjustment of Ti and V contents,an intrinsic ductility mechanism was unveiled,manifested by a transition from predominant intergranular brittle fracture to pervasive ductile dimpled rupture.Notably,the modulated deformation mechanisms evolved from solitary slip toward collaborative multiple slip modes,without significantly compromising strength.Compared to equimolar Ti-V-Zr-Nb,a(Ti1.5V)3ZrNb composition demonstrated an impressive 360%improvement in elongation while sustaining a high yield strength of around 800 MPa.Increasing Ti and V not only purified the grain boundaries by reducing detrimental phases,but also tai-lored the deformation dislocation configurations.These insights expanded the applicability of lightweight HEAs to areas demanding combined high strength and ductility.
基金supported by the National Natural Science Foundation of China(No.52061135101 and 52001078)the German Research Foundation(DFG,No.448318292)+3 种基金the Technology Innovation Guidance Special Foundation of Shaanxi Province(No.2023GXLH-085)the Fundamental Research Funds for the Central Universities(No.D5000240161)the Project of Key areas of innovation team in Shaanxi Province(No.2024RS-CXTD-20)The author Yingchun Xie thanks the support from the National Key R&D Program(No.2023YFE0108000).
文摘1.Introduction.Cold Spray(CS)is a highly advanced solid-state metal depo-sition process that was first developed in the 1980s.This innovative technique involves the high-speed(300-1200 m/s)impact deposition of micron-sized particles(5-50μm)to fabricate coatings[1-3].CS has been extensively used in a variety of coating applications,such as aerospace,automotive,energy,medical,marine,and others,to provide protection against high temperatures,corrosion,erosion,oxidation,and chemicals[4,5].Nowadays,the technical interest in CS is twofold:(i)as a repair process for damaged components,and(ii)as a solid-state additive manufacturing process.Compared to other fusion-based additive manufacturing(AM)technologies,Cold Spray Additive Manufacturing(CSAM)is a new member of the AM family that can enable the fabrication of deposits without undergoing melting.The chemical composition has been largely preserved from the powder to the deposit due to the minimal oxidation.The significant advantages of CSAM over other additive manufacturing processes include a high production rate,unlimited deposition size,high flexibility,and suitability for repairing damaged parts.
基金supported by the National Key R&D Program of China(No.2019YFA0209902)the Natural Science Foundation of China(Nos.52071326,52192593,51601204)+1 种基金the NSFC Basic Science Center Program for Multiscale Problems in Nonlinear Mechanics(No.11988102)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB22040503).
文摘A newly developed P-doped CrCoNi medium-entropy alloy(MEA)provides both higher yield strength and larger uniform elongation than the conventional CrCoNi MEA,even superior tensile ductility to the other-element-doped CrCoNi MEAs at similar yield strength levels.P segregation at grain boundaries(GBs)and dissolution inside grain interiors,together with the related lower stacking fault energy(SFE)are found in the P-doped CrCoNi MEA.Higher hetero-deformation-induced(HDI)hardening rate is observed in the P-doped CrCoNi MEA due to the grain-to-grain plastic deformation and the dynamic structural refinement by high-density stacking fault-walls(SFWs).The enhanced yield strength in the P-doped CoCrNi MEA can be attributed to the strong substitutional solid-solution strengthening by severer lattice distortion and the GB strengthening by phosphorus segregation at GBs.During the tensile deformation,the multiple SFW frames inundated with massive multi-orientational tiny planar stacking faults(SFs)between them,rather than deformation twins,are observed to induce dynamic structural refinement for forming par-allelepiped domains in the P-doped CoCrNi MEA,due to the lower SFE and even lower atomically-local SFE.These nano-sized domains with domain boundary spacing at tens of nanometers can block disloca-tion movement for strengthening on one hand,and can accumulate defects in the interiors of domains for exceptionally high hardening rate on the other hand.
基金funding from the National Natural Science Foundation of China(Nos.52063017 and 52061025)the Major Science and Technology Project of Gansu Province(Nos.22ZD6GA008 and 20ZD7GJ008)+3 种基金the Natural Science Foundation of Gansu Province(No.23JRRA820)The Science and Technology Project of Major Science and Technology Project of Gansu Province(No.22ZD6GA008)the Science and Technology Project of Gansu Province(No.23YFGA0058)the College Industry Support Plan of Gansu Province(No.2023CYZC-27).
文摘The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17 %–34 % Ni, 33 %–50 % Co, and 25 %–33 % Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.
文摘The rapid progress in the construction of heavy-haul and high-speed railways has led to a surge in rail defects and unforeseen failures.Addressing this issue necessitates the implementation of more sophisticated rail inspection methods,specifically involving real-time,precise detection,and assessment of rail defects.Current applications fail to address the evolving requirements,prompting the need for advancements.This paper provides a summary of various types of rail defects and outlines both traditional and innovative non-destructive inspection techniques,examining their fundamental features,benefits,drawbacks,and practical suitability for railway track inspection.It also explores potential enhancements to equipment and software.The comprehensive review draws upon pertinent international research and review papers.Furthermore,the paper introduces a fusion of inspection methods aimed at enhancing the overall reliability of defect detection.
文摘The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analysis of bridge inspection materials,the principle of ultrasonic non-destructive testing technology and its adaptability to bridge engineering are elaborated.Subsequently,starting from the preparation work before inspection until damage assessment,the entire process of ultrasonic non-destructive testing is studied,and finally,a technical system of ultrasonic non-destructive testing for bridge engineering that runs through the entire process is formed.It is hoped that this article can provide technical reference value for relevant units in China,and promote the high-quality development of China’s bridge engineering from a macro perspective.
基金supported by the“National Ocean Technology Center Innovation Fund”under Project No.N3220Z002,led by Ning Jia.The official website of the National Ocean Technology Center is accessible at:http://www.notcsoa.org.cn/.
文摘With the depletion of fossil fuels and increasing environmental concerns,the development of renewable energy,such as wave energy,has become a critical component of global energy strategies.However,challenges persist in the field testing methodologies for wave energy converters(WECs).In this paper,a numerical wave field of the Dawanshan Island Sea Area in Zhuhai City is constructed based on the MIKE21 SW wave model and by using an NCEP wind field driving model.In conjunction with the IEC-62600-100 standard,by taking site testing of the“Wanshan”wave energy converter on which a sea trial has been conducted in Dawanshan Island of Zhuhai city as an example,research on-site testing method for a wave energy converter has been carried out.The wave measurement position for the“Wanshan”converter was determined by combining statistically analyzed field data with a validated numerical wave model.By comparing a valid wave height at the position where a wave rider is located with a valid wave height at the position where the“Wanshan”wave energy converter is situated,the correlation coefficient between simulation and observed data reached 0.90,with a root-mean-square error of 0.19.The representativeness of wave measurement data during site testing is verified and can be used as a basis for calculating the input energy of the“Wanshan”wave energy converter.
基金The National Natural Science Foundation of China(No.5117810151378112)the Doctoral Fund of Ministry of Education(No.20110092110011)
文摘To study the seismic performance of double-skin steelconcrete composite box（ DSCB） piers, a total of 11 DSCB pier specimens were tested under bidirectional cyclic loading. The effects of the loading pattern, the steel plate thickness, the axial load ratio, the slenderness ratio and the aspect ratio were taken into consideration. The damage evolution process and failure modes of the tested specimens are presented in detail. Test results are also discussed in terms of the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of DSCB pier specimens. It can be concluded that the hysteretic performance of DSCB piers in one direction is affected and weakened by the cyclic loading in the other direction. DSCB piers under bidirectional cyclic loading exhibit good performance in terms of load carrying capacity, ductility, and energy dissipation capacity. Overall, DSCB piers can meet the basic aseismic requirements. The research results can be taken as a reference for using DSCB piers as high piers in bridges in strong earthquakeprone areas.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars(Grant No.42225206)National Natural Science Foundation of China(42207180,42477209,42302320).
文摘Subgrade engineering is a fundamental aspect of infrastructure construction in China.As the primary structural element responsible for bearing and distributing traffic loads,the subgrade must not only withstand the substantial pressures exerted by vehicles,trains,and other forms of transportation,but also efficiently transfer these loads to the underlying foundation,ensuring the stability and longevity of the roadway.In recent years,advancements in subgrade engineering technology have propelled the industry towards smarter,greener,and more sustainable practices,particularly in the areas of intelligent monitoring,disaster management,and innovative construction methods.This paper reviews the application and methodologies of intelligent testing equipment,including cone penetration testing(CPT)devices,soil resistivity testers,and intelligent rebound testers,in subgrade engineering.It examines the operating principles,advantages,limitations,and application ranges of these tools in subgrade testing.Additionally,the paper evaluates the practical use of advanced equipment from both domestic and international perspectives,addressing the challenges encountered by various instruments in realworld applications.These devices enable precise,comprehensive testing and evaluation of subgrade conditions at different stages,providing real-time data analysis and intelligent early warnings.This supports effective subgrade health management and maintenance.As intelligent technologies continue to evolve and integrate,these tools will increasingly enhance the accuracy,efficiency,and sustainability of subgrade monitoring.
文摘Point-of-care testing(POCT)refers to a category of diagnostic tests that are performed at or near to the site of the patients(also called bedside testing)and is capable of obtaining accurate results in a short time by using portable diagnostic devices,avoiding sending samples to the medical laboratories.It has been extensively explored for diagnosing and monitoring patients’diseases and health conditions with the assistance of development in biochemistry and microfluidics.Microfluidic paper-based analytical devices(μPADs)have gained dramatic popularity in POCT because of their simplicity,user-friendly,fast and accurate result reading and low cost.SeveralμPADs have been successfully commercialized and received excellent feedback during the past several decades.This review briefly discusses the main types ofμPADs,preparation methods and their detection principles,followed by a few representative examples.The future perspectives of the development inμPADs are also provided.
基金financially supported by the National Key Research&Development Plan(No.2022YFE0110600)the National Natural Science Foundation of China(Nos.52171117,52371113,92263201 and 52175306)+3 种基金Qing Lan Project(No.54944004)the Basic Research Program of Jiangsu(Nos.BK20232011 and BK20232025)the Postdoctoral Fellowship Program of CPSF(No.GZC20233481)Tuoyuan project of Nanjing Tech University(No.20230113)
文摘Strain rate is a critical factor influencing the mechanical response of hexagonal close-packed titanium under cryogenic conditions.In this study,uniaxial tensile tests were performed on commercially pure titanium at 77 K over a broad strain rate range from 0.001 to 1 s^(-1).A critical strain rate of approximately 0.5 s^(-1)was identified,above which ductility exhibits a pronounced reduction,whereas below this threshold,ductility remains relatively stable.Through comprehensive analyses of strain evolution,deformed microstructure,and fracture morphology,this behavior is attributed to severe localized adiabatic heating resulting from inhomogeneous deformation,rather than conventional twin or shear mechanisms.
基金supported by the National Key R&D program of China(No.2022YFB3705704)the Natural Science Foundation of Heilongjiang Province of China(No.YQ2023E007)+2 种基金the National Natural Science Foundation of China(Nos.52201116,52071228 and 52271118)the State Key Laboratory of Advanced Welding and Joining,the Harbin Institute of Technology(No.AWJ-23M24)the funding Shi Changxu Innovation Center for Advanced Materials(No.SCXKFJJ202213)。
文摘A novel triplex heat treatment was designed to simultaneously improve the high-temperature strength and ductility of titanium matrix composites(TMCs)by modulating the microstructure and(TiB+TiC)reinforcements and promoting the precipitation of(Ti,Zr)_(6)Si_(3) silicides and theα2 phase.
文摘Penetration testing plays a critical role in ensuring security in an increasingly interconnected world. Despite advancements in technology leading to smaller, more portable devices, penetration testing remains reliant on traditional laptops and computers, which, while portable, lack true ultra-portability. This paper explores the potential impact of developing a dedicated, ultra-portable, low-cost device for on-the-go penetration testing. Such a device could replicate the core functionalities of advanced penetration testing tools, including those found in Kali Linux, within a compact form factor that fits easily into a pocket. By offering the convenience and portability akin to a smartphone, this innovative device could redefine the way penetration testers operate, enabling them to carry essential tools wherever they go and ensuring they are always prepared to conduct security assessments efficiently. This approach aims to revolutionize penetration testing by merging high functionality with unparalleled portability.
基金support from the National Science Foundation of China(No.52071037)Zhejiang province science and technology planning project(No.2022C01008).
文摘In this research,a high ductility Mg-Gd-Mn magnesium alloy was designed and developed,with an elongation capability surpassing 50%.To gain insights into the underlying mechanism behind the high ductility of the Mg-2Gd-0.5Mn alloy,quasi-in-situ electron backscattered diffraction and two-beam diffraction were conducted.The results reveal that the Mg-Gd-Mn alloy exhibits a distinct rare-earth texture,and the activation of non-basal slip systems is evident from the clear observation of non-basal slip traces during the later stages of deformation.However,the primary deformation mechanisms in Mg-Gd-Mn alloy remain basalslip and{10–12}tensile twinning,and the remarkable ductility observed in Mg-Gd-Mn alloys can be attributed to the softening of non-basal slip modes,which leads to a coordinated deformation between various modes of deformation.To further validate this conclusion,an analysis was conducted using a visco-plastic self-consistent(VPSC)model to investigate the relative activity of basal and non-basal slip in Mg-Gd-Mn alloys.The obtained results align well with experimental observations,providing additional support for the hypothesis.
