Modem dynamic tests such as networked collaborative pseudo-dynamic testing （PDT） provide new tools to study the dynamic performance of large and complex structures. In this paper, several networked collaborative PDT...Modem dynamic tests such as networked collaborative pseudo-dynamic testing （PDT） provide new tools to study the dynamic performance of large and complex structures. In this paper, several networked collaborative PDT systems established in China and abroad are introduced, including a detailed description of the first networked collaborative platform that involved the construction of a standardized demonstration procedure for networked collaborative PDT. The example is a multi-span bridge with RC piers retrofitted by FRP, and a networked structural laboratory （NetSLab） platform is used to link distributed laboratories located at several universities together. Substructure technology is also used in the testing. The characteristics, resource sharing and collaborative work of NetSLab are described, and the results illustrate that use of the NetSLab is feasible for studying the dynamic performance of multi-span bridge structures.展开更多
A pseudo-dynamic testing program was generated on a fabricated composite frame with steel plate shear walls （SPSWs） to study its seismic perlbrmance. The specimen was a three-storey single-bay frame, which was compo...A pseudo-dynamic testing program was generated on a fabricated composite frame with steel plate shear walls （SPSWs） to study its seismic perlbrmance. The specimen was a three-storey single-bay frame, which was composed of H- section steel columns and composite beams, and was assembled by bolted height-adjustable steel beam-to-column connections （BHA connections）. Beam-only-connected SPSWs were selected as lateral load resisting members. The specimen was subjected to four ground motions of progressively increasing intensity. The results showed that： （1） beam-only-connected S PSWs provided sufficient lateral load resistance, lateral stiffness, and energy dissipation capacity to the fabricated frame via the tension ficld action developed in their infill panels; （2） the fabricated frame, assembled by BHA connections, exhibited substantial redundancy and good ductility; （3） an undesirable failure mode of the fabricated frame, in huge earthquakes, included severe cracking in composite beams and block shear failure in SPSWs＇ connections; （4） the inter-storey shear force distribution determined by ASCE/SE1 7-10 was verified with experimental data.展开更多
Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically mode...Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically modeled, while the base isolation layer is considered as the experimental substructure in the pseudo-dynamic tests. The test result verifies that the STRP isolator shows acceptable shear deformation performance predicted by the design methods, and demonstrated that seismic isolation using STRP works as a protective measure to provide enhanced seismic performance of the building indicated by the reduction of top floor absolute acceleration, drift and base shear as designated.展开更多
A retrofitting technology using precast steel reinforced concrete（PSRC） panels is developed to improve the seismic performance of old masonry buildings. The PSRC panels are built up as an external PSRC wall system s...A retrofitting technology using precast steel reinforced concrete（PSRC） panels is developed to improve the seismic performance of old masonry buildings. The PSRC panels are built up as an external PSRC wall system surrounding the existing masonry building. The PSRC walls are well connected to the existing masonry building, which provides enough confinement to effectively improve the ductility, strength, and stiffenss of old masonry structures. The PSRC panels are prefabricated in a factory, significantly reducing the situ work and associated construction time. To demonstrate the feasibility and mechanical effectivenss of the proposed retrofitting system, a full-scale five-story specimen was constructed. The retrofitting process was completed within five weeks with very limited indoor operation. The specimen was then tested in the lateral direction, which could potentially suffer sigifnicant damage in a large earthquake. The technical feasibility, construction workability, and seismic performance were thoroughly demonstrated by a full-scale specimen construction and pseudo-dynamic tests.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
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
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
Geomechanical properties of rocks vary across different measurement scales,primarily due to heterogeneity.Micro-scale geomechanical tests,including micro-scale“scratch tests”and nano-scale nanoindentation tests,are ...Geomechanical properties of rocks vary across different measurement scales,primarily due to heterogeneity.Micro-scale geomechanical tests,including micro-scale“scratch tests”and nano-scale nanoindentation tests,are attractive at different scales.Each method requires minimal sample volume,is low cost,and includes a relatively rapid measurement turnaround time.However,recent micro-scale test results–including scratch test results and nanoindentation results–exhibit tangible variance and uncertainty,suggesting a need to correlate mineral composition mapping to elastic modulus mapping to isolate the relative impact of specific minerals.Different research labs often utilize different interpretation methods,and it is clear that future micro-mechanical tests may benefit from standardized testing and interpretation procedures.The objectives of this study are to seek options for standardized testing and interpretation procedures,through two specific objectives:(1)Quantify chemical and physical controls on micro-mechanical properties and(2)Quantify the source of uncertainties associated with nanoindentation measurements.To reach these goals,we conducted mechanical tests on three different scales:triaxial compression tests,scratch tests,and nanoindentation tests.We found that mineral phase weight percentage is highly correlated with nanoindentation elastic modulus distribution.Finally,we conclude that nanoindentation testing is a mineralogy and microstructure-based method and generally yields significant uncertainty and overestimation.The uncertainty of the testing method is largely associated with not mapping pore space a priori.Lastly,the uncertainty can be reduced by combining phase mapping and modulus mapping with substantial and random data sampling.展开更多
The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSN...The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.展开更多
Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects...Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.展开更多
Knowledge of the dynamic modulus of bituminous mixtures is practical and theoretically meaningful in pavement design,construction,and monitoring.The tests in the laboratory for the determination of asphalt concrete(AC...Knowledge of the dynamic modulus of bituminous mixtures is practical and theoretically meaningful in pavement design,construction,and monitoring.The tests in the laboratory for the determination of asphalt concrete(AC)moduli include the resilient modulus through the indirect tensile test(EN 12697-26),the complex modulus through the four point bending beam(EN 12697-26),the asphalt mixture performance tester(AMPT)and the simple performance tester(SPT)(AASHTO T342).Unfortunately,the tests above are time-consuming and quite expensive.On the other hand,the standard ASTM E1876 for resonant tests applies only to very thin(stocky)cylindrical samples(with a thickness-to-radius ratio,t/r,lower than 0.5)while the typical AC samples produced in the laboratory do not satisfy the ASTM E1876 requirements.Consequently,the main objective of this study is to set up and implement a tentative method to extend the range of applicability of the standard ASTM E1876 to common AC samples.The methodology was to carry out resonant tests on slender samples and to cut each of them into stocky samples(these latter complying with ASTM E1876 requirements in terms of t/r),deriving the master curve per material.These master curves allowed for deriving the value of the dynamic modulus for the given selected sample under its particular test conditions during the resonant test(i.e.,temperature and frequency).Consequently,simplified formulae were provided for AC samples.Results were compared to Witczak's estimates.These formulae provide an approximate tool to carry out low-cost and high-speed inferences at the laboratory stage on common AC samples,whatever their thickness is.Additional studies are needed to investigate the reliability of the method further and reduce uncertainties.展开更多
In recent years,the application scenarios of electrical and electronic products have become increasingly diverse worldwide.The impact of climatic environmental tests on the performance of related products has attracte...In recent years,the application scenarios of electrical and electronic products have become increasingly diverse worldwide.The impact of climatic environmental tests on the performance of related products has attracted much attention,and formulating scientific and reasonable environmental test plans has become an important step to ensure product quality and reliability.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
This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of fun...This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of functional modules,signal processing modules,and data analysis modules,and covers aspects such as the application of machine learning algorithms and the establishment of fault waveform databases.Finally,it looks forward to the development of intelligent testing systems and emphasizes the importance of building a standardized testing system.展开更多
With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective o...With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective of this article is to determine optimal measurement grids for SISO OTA testing of 5G Sub-6 GHz user equipments(UEs)in anechoic chamber with satisfactory accuracy and efficiency.The effect of different grid configurations on OTA performance is analyzed quantitatively using reference radiation patterns at different bands.These patterns are utilized to mimic the worst-case radiation patterns of 5G Sub-6 GHz UEs.Subsequently,the associated measurement uncertainty(MU)terms are quantitatively analyzed and determined based on statistical analysis.According to the comparison of calculated MUs,reduction of grid points from currentlyrequired 62(30/30,Δθ/Δϕ)to 26(45/45)could achieve roughly 60%test time reduction for Sub-6 GHz,while still maintaining an uncertainty level of≤0.25 dB.These values can be further reduced to 14(60/60)with 80%reduction for Sub-3 GHz.More importantly,the recommended grid configurations in this research are applicable to both TIS and TRP testing.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
基金The Key Project of the Major Research Plan of Natural Science Foundation of China Under Grant No.90715036the Key Project of the Natural Science Foundation of China Under Grant No.50338020
文摘Modem dynamic tests such as networked collaborative pseudo-dynamic testing （PDT） provide new tools to study the dynamic performance of large and complex structures. In this paper, several networked collaborative PDT systems established in China and abroad are introduced, including a detailed description of the first networked collaborative platform that involved the construction of a standardized demonstration procedure for networked collaborative PDT. The example is a multi-span bridge with RC piers retrofitted by FRP, and a networked structural laboratory （NetSLab） platform is used to link distributed laboratories located at several universities together. Substructure technology is also used in the testing. The characteristics, resource sharing and collaborative work of NetSLab are described, and the results illustrate that use of the NetSLab is feasible for studying the dynamic performance of multi-span bridge structures.
基金Project supported by the National Natural Science Foundation of China （No. 51378147）
文摘A pseudo-dynamic testing program was generated on a fabricated composite frame with steel plate shear walls （SPSWs） to study its seismic perlbrmance. The specimen was a three-storey single-bay frame, which was composed of H- section steel columns and composite beams, and was assembled by bolted height-adjustable steel beam-to-column connections （BHA connections）. Beam-only-connected SPSWs were selected as lateral load resisting members. The specimen was subjected to four ground motions of progressively increasing intensity. The results showed that： （1） beam-only-connected S PSWs provided sufficient lateral load resistance, lateral stiffness, and energy dissipation capacity to the fabricated frame via the tension ficld action developed in their infill panels; （2） the fabricated frame, assembled by BHA connections, exhibited substantial redundancy and good ductility; （3） an undesirable failure mode of the fabricated frame, in huge earthquakes, included severe cracking in composite beams and block shear failure in SPSWs＇ connections; （4） the inter-storey shear force distribution determined by ASCE/SE1 7-10 was verified with experimental data.
文摘Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically modeled, while the base isolation layer is considered as the experimental substructure in the pseudo-dynamic tests. The test result verifies that the STRP isolator shows acceptable shear deformation performance predicted by the design methods, and demonstrated that seismic isolation using STRP works as a protective measure to provide enhanced seismic performance of the building indicated by the reduction of top floor absolute acceleration, drift and base shear as designated.
基金Scientific Research Fund of Institute of Engineering Mechanics,CEA under Grant No.2016A06International Science & Technology Cooperation Program of China under Grant No.2014DFA70950National Natural Science Foundation of China under Grant Nos.51378478,51161120360
文摘A retrofitting technology using precast steel reinforced concrete（PSRC） panels is developed to improve the seismic performance of old masonry buildings. The PSRC panels are built up as an external PSRC wall system surrounding the existing masonry building. The PSRC walls are well connected to the existing masonry building, which provides enough confinement to effectively improve the ductility, strength, and stiffenss of old masonry structures. The PSRC panels are prefabricated in a factory, significantly reducing the situ work and associated construction time. To demonstrate the feasibility and mechanical effectivenss of the proposed retrofitting system, a full-scale five-story specimen was constructed. The retrofitting process was completed within five weeks with very limited indoor operation. The specimen was then tested in the lateral direction, which could potentially suffer sigifnicant damage in a large earthquake. The technical feasibility, construction workability, and seismic performance were thoroughly demonstrated by a full-scale specimen construction and pseudo-dynamic tests.
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.
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 of this project through the Southwest Regional Partnership on Carbon Sequestration(Grant No.DE-FC26-05NT42591)Improving Production in the Emerging Paradox Oil Play(Grant No.DE-FE0031775).
文摘Geomechanical properties of rocks vary across different measurement scales,primarily due to heterogeneity.Micro-scale geomechanical tests,including micro-scale“scratch tests”and nano-scale nanoindentation tests,are attractive at different scales.Each method requires minimal sample volume,is low cost,and includes a relatively rapid measurement turnaround time.However,recent micro-scale test results–including scratch test results and nanoindentation results–exhibit tangible variance and uncertainty,suggesting a need to correlate mineral composition mapping to elastic modulus mapping to isolate the relative impact of specific minerals.Different research labs often utilize different interpretation methods,and it is clear that future micro-mechanical tests may benefit from standardized testing and interpretation procedures.The objectives of this study are to seek options for standardized testing and interpretation procedures,through two specific objectives:(1)Quantify chemical and physical controls on micro-mechanical properties and(2)Quantify the source of uncertainties associated with nanoindentation measurements.To reach these goals,we conducted mechanical tests on three different scales:triaxial compression tests,scratch tests,and nanoindentation tests.We found that mineral phase weight percentage is highly correlated with nanoindentation elastic modulus distribution.Finally,we conclude that nanoindentation testing is a mineralogy and microstructure-based method and generally yields significant uncertainty and overestimation.The uncertainty of the testing method is largely associated with not mapping pore space a priori.Lastly,the uncertainty can be reduced by combining phase mapping and modulus mapping with substantial and random data sampling.
文摘The China Spallation Neutron Source(CSNS)is the fourth pulsed accelerator-driven neutron source in the world,and it achieved its design target of 100 kW in 2020.The planned China Spallation Neutron Source Phase II(CSNS-II)commenced in 2024.The CSNS-II linac design primarily involves the addition of a radio-frequency ion source and a section of a superconducting linear accelerator composed of two types of superconducting cavities,namely double-spoke and six-cell elliptical cavities,after the drift tube linac(DTL).The development of the double-spoke superconducting cavity began in early 2021,and by January 2023,the welding,post-processing,and vertical tests of two 324 MHz double-spoke cavity prototypes were completed,with vertical test gradients of 11.6 and 15 MV/m,and Q_(0)≥3×10^(10)@E_(acc)≤10 MV/m.The R&D of the cryomodule began in January 2022.In October 2023,the clean assembly of the double-spoke cavity string and cold mass installation of the cryomodule commenced,with the installation of the cryomodule and valve box completing in two months.In January 2024,a horizontal test of the cryomodule was completed,making it the first double-spoke cavity cryomodule in China.The test results showed that the maximum gradients of the two superconducting cavities at a pulse width of 4 ms and repetition frequency of 25 Hz were 12.8 and 15.2 MV/m,respectively.This article provides a detailed introduction to the double-spoke superconducting cavity,tuner,coupler,and cryomodule,elaborates on the clean assembly of the cavity string and cold mass installation of the cryomodule,and provides a detailed analysis of the horizontal test results.
基金funding support from the National Natural Science Foundation of China(Grant No.42072303)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(Grant No.SKLGP2021Z004).
文摘Earthquakes contribute to the failure of anti-dip bedding rock slopes(ABRSs)in seismically active regions.The pseudo-static method is commonly employed to assess the ABRSs stability.However,simplifying seismic effects as static loads often underestimates rock slope stability.The development of a practical stability analysis approach for ABRSs,particularly in slope engineering design,is imperative.This study proposes a stability evaluation model for ABRSs,incorporating the viscoelastic properties of rock,to quantitatively assess the safety factor and failure surface under seismic conditions.The mathematical description of the pseudo-dynamic method,derived in this study,accounts for the viscoelastic properties of ABRSs and integrates the HoekeBrown failure criterion with the Kelvin-Voigt stress-strain relationship of rocks.Furthermore,to address concurrent translation-rotation failure in ABRSs,upper bound limit analysis is utilized to quantify the safety factor.Through a comparison with existing literature,the proposed method considers the effect of harmonic vibration on the stability of ABRSs.The obtained safety factor is lower than that of the quasi-static method,with the resulting percentage change exceeding 5%.The critical failure surface demonstrates superior positional accuracy compared to the Aydan and Adhikary basal planes,with minimal error observed between the physical model test and the numerical simulation test.The parameter sensitivity analysis reveals that the inclination of ABRSs exhibits the highest sensitivity(Sk)value across the three levels of horizontal seismic coefficient(kh).The study aims to devise an expeditious calculation approach for assessing the stability of ABRSs during seismic events,intending to offer theoretical guidance for their stability analysis.
文摘Knowledge of the dynamic modulus of bituminous mixtures is practical and theoretically meaningful in pavement design,construction,and monitoring.The tests in the laboratory for the determination of asphalt concrete(AC)moduli include the resilient modulus through the indirect tensile test(EN 12697-26),the complex modulus through the four point bending beam(EN 12697-26),the asphalt mixture performance tester(AMPT)and the simple performance tester(SPT)(AASHTO T342).Unfortunately,the tests above are time-consuming and quite expensive.On the other hand,the standard ASTM E1876 for resonant tests applies only to very thin(stocky)cylindrical samples(with a thickness-to-radius ratio,t/r,lower than 0.5)while the typical AC samples produced in the laboratory do not satisfy the ASTM E1876 requirements.Consequently,the main objective of this study is to set up and implement a tentative method to extend the range of applicability of the standard ASTM E1876 to common AC samples.The methodology was to carry out resonant tests on slender samples and to cut each of them into stocky samples(these latter complying with ASTM E1876 requirements in terms of t/r),deriving the master curve per material.These master curves allowed for deriving the value of the dynamic modulus for the given selected sample under its particular test conditions during the resonant test(i.e.,temperature and frequency).Consequently,simplified formulae were provided for AC samples.Results were compared to Witczak's estimates.These formulae provide an approximate tool to carry out low-cost and high-speed inferences at the laboratory stage on common AC samples,whatever their thickness is.Additional studies are needed to investigate the reliability of the method further and reduce uncertainties.
文摘In recent years,the application scenarios of electrical and electronic products have become increasingly diverse worldwide.The impact of climatic environmental tests on the performance of related products has attracted much attention,and formulating scientific and reasonable environmental test plans has become an important step to ensure product quality and reliability.
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This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of functional modules,signal processing modules,and data analysis modules,and covers aspects such as the application of machine learning algorithms and the establishment of fault waveform databases.Finally,it looks forward to the development of intelligent testing systems and emphasizes the importance of building a standardized testing system.
基金supported by the Beijing Natural Science Foundation under Grant L253002.
文摘With the rapid development and commercialization of wireless communications,the execution of OTA testing requires a tremendous amount of test time.Therefore,test time reduction is of great significance.The objective of this article is to determine optimal measurement grids for SISO OTA testing of 5G Sub-6 GHz user equipments(UEs)in anechoic chamber with satisfactory accuracy and efficiency.The effect of different grid configurations on OTA performance is analyzed quantitatively using reference radiation patterns at different bands.These patterns are utilized to mimic the worst-case radiation patterns of 5G Sub-6 GHz UEs.Subsequently,the associated measurement uncertainty(MU)terms are quantitatively analyzed and determined based on statistical analysis.According to the comparison of calculated MUs,reduction of grid points from currentlyrequired 62(30/30,Δθ/Δϕ)to 26(45/45)could achieve roughly 60%test time reduction for Sub-6 GHz,while still maintaining an uncertainty level of≤0.25 dB.These values can be further reduced to 14(60/60)with 80%reduction for Sub-3 GHz.More importantly,the recommended grid configurations in this research are applicable to both TIS and TRP testing.
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.
