This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable ...This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable bolts has received limited experimental attention,and their effectiveness in seismically active zones remains a subject of ongoing debate.To address this gap,a reverse pull-out test machine integrated with a drop hammer rig was employed.Tests were conducted on 70-t SUMO bulbed and non-bulbed cable bolts with encapsulation lengths of 300 and 450 mm,subjected to an impact energy of 14.52 k J.Results indicate that non-bulbed cables,despite showing lower initial peak loads(average 218 vs.328 k N for bulbed cables at 300 mm encapsulation),demonstrated superior energy absorption(average 11.26 vs.8.75 k J)and displacement capacity(average 48.40 vs.36.25 mm).Increasing the encapsulation length for bulbed cables led to a reduction in initial peak load but improved displacement and energy absorption.The dominant failure mechanism was debonding at the cable-grout interface,characterised by frictional sliding and cable rotation.These findings provide new insights into the energy dissipation mechanisms of cables and support the development of more resilient ground support systems for dynamically active conditions.展开更多
The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varyi...The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varying degrees of degradation and damage to the main cable,necessitating regular inspections to prevent catastrophic failures.Traditional manual inspection methods not only suffer from low efficiency but also pose significant safety risks to personnel.To address these challenges and ensure the safe and effective inspection of suspension bridge main cables,this study introduces a novel cooperative climbing robot,designated as Main Cable Robot Version II(CCRobot-M-II),inspired by the locomotion of the inchworm.The robot employs an alternating opening and closing mechanism of four gripper sets,mimicking the inchworm's movement to achieve efficient crawling along the suspension bridge handrails.This paper provides a comprehensive analysis of the structural design,key components,and motion mechanisms of CCRobot-M-II.A detailed force analysis of the robot's crawling process is also presented,followed by the design of the control system and the development of an efficient motion control algorithm.Laboratory experiments demonstrate that the robot achieves a positional error of 00.64%during crawling,with a maximum average crawling speed of 7.6 m/min.Furthermore,the biomimetic design enables the robot to overcome obstacles up to 30 mm in height and possess the capability to handle suspension bridge cables with spans ranging from 740 to 1100 mm.Finally,CCRobot-M-II successfully conducted an inspection of the main cable on a suspension bridge,marking the world's first successful deployment of a climbing robot for main cable inspection on a suspension bridge.展开更多
In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory mode...In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory model tests with FLAC3D simulations to evaluate the stabilizing role of prestressed anchor cables and to establish an energy-balance framework for support optimization.Comparative model tests of existing and enlarged tunnel sections,with and without anchors,show that reinforcement increases load-carrying capacity,reduces displacement,and confines damage to more localized zones.The numerical simulations reproduce displacement fields,shear-strain localization,and plastic-zone evolution with good agreement against the experimental observations.The energy framework is implemented in the in-situ simulations by quantifying unloading-related energy release in the rock mass and reinforcement work contributed by the anchors,and by introducing an energy release–reinforcement ratio as a stability indicator.Parametric analyses indicate that anchor length,spacing,and prestress influence stability in a nonlinear manner,with diminishing returns once reinforcement extends beyond the mechanically dominant deformation zone.An efficient parameter window is identified that improves deformation and yielding control while avoiding unnecessary reinforcement.The results provide an energy-consistent and design-oriented basis for prestressed anchorage selection in large-span tunnel expansion.展开更多
This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extru...This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extruded cable systems for power transmission at a rated voltage up to 800 kV’because it has a fairly similar structure to CIGRE TB 853:2021 for lapped DC cables,and especially because of the impressive spread of HVDC extruded cables experienced worldwide in the last 25 years.The review considers development tests,pre-qualification tests,extension of qualification test,type tests(with hints at IEEE 1732-2017 for space charge measurements in the qualification of HVDC extruded cables),routine tests(with hints at IEEE 2862-2020 for routine tests of HVDC extruded cable system joints),sample tests and after installation tests.The review also analyses CIGRE TB 853 for lapped HVDC cable systems,as these cables remain unbeaten for submarine applications at the highest sea depths.The main novelties of CIGRE TB 852 and 853 with respect to previous standards for HVDC cable systems(mainly CIGRE TB 496 and IEC 62895 for extruded cables and CIGRE Electra 189:2000 for lapped cables)are put under the spotlight-with focus on the so-called temporary over-voltage tests-together with the limits and gaps of CIGRE TB 852.The main HVDC cable system testing equipment that is usually employed for electro-thermal tests is also treated.Emphasis is given to CIGRE TB 490 to treat the peculiarities of submarine cable systems,as well as to mechanical tests,having CIGRE TB 623 as a reference,with particular focus on the special sea trial tests.An example of an innovative sea trial testing procedure is shown,which is the outcome of a fruitful partnership between a cable manufacturer and the national Transmission System Operator in Italy.展开更多
The actively heated fiber-optic(AHFO)technology has emerged as a frontier and hotspot in soil water content measurement,offering advantages such as easy installation,large-scale distributed measurement capability,and ...The actively heated fiber-optic(AHFO)technology has emerged as a frontier and hotspot in soil water content measurement,offering advantages such as easy installation,large-scale distributed measurement capability,and resistance to electromagnetic interference.However,current AHFO water content sensors fail to simultaneously achieve high precision,applicability for deep soil,and automated real-time monitoring,thereby limiting their development and application.Therefore,this study introduces a novel actively heated fiber Bragg grating(AH-FBG)cable.Laboratory tests were conducted to assess the heating uniformity of the AH-FBG cable and to establish the temperature characteristic value(T_(t))-soil water content(θ)calibration formula for water content measurement.Subsequently,AH-FBG cables were deployed for in situ soil water content monitoring in a test pit on the Loess Plateau.Through two-year monitoring data verified the accuracy of the AH-FBG cable and elucidated the spatiotemporal distribution of in situ loess water content.Laboratory results demonstrated superior heating uniformity of AHFBG cable,with a T_(t) standard deviation of approximately 0.3℃.In the field,the AH-FBG cable exhibited excellent performance in soil water content measurement,achieving a high accuracy of 0.023 cm^(3)/cm^(3).Further analysis revealed that the θ fluctuation predominantly occurred within a 10 m depth from the soil surface,with an overall upward trend over the two-year monitoring period;the response of shallow θ to precipitation was significant but exhibited increasing hysteresis with depth;frequent precipitation significantly enhanced water infiltration depth.This study provides technical guidance for highprecision,quasi-distributed,automated and real-time water content measurement of deep soil.展开更多
Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins ar...Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins are limited,especially in automation,heavily dependent on large amounts of data and resources,lacking the flexibility to adapt to different scenarios.To address these challenges,this paper introduces a novel image segmentation model,CableSAM,specifically designed for automated segmentation of cabin cables.CableSAM improves segmentation efficiency and accuracy using knowledge distillation and employs a context ensemble strategy.It accurately segments cables in various scenarios with minimal input prompts.Comparative experiments on three cable datasets demonstrate that CableSAM surpasses other advanced cable segmentation methods in performance.展开更多
Charge dynamics at interfaces in high voltage direct current(HVDC)cable joints consisting of cable,joint insulation and lubricant may have an impact on the overall joint reliability.Although interactions between diffe...Charge dynamics at interfaces in high voltage direct current(HVDC)cable joints consisting of cable,joint insulation and lubricant may have an impact on the overall joint reliability.Although interactions between different lubricants and the joint insulation have been studied in recent years,the effect of lubricant diffusion on the electrical properties and charge dynamics at interfaces remains unclear and is therefore investigated in this paper.Different lubricants were applied at the interface of crosslinked polyethylene(XLPE)and silicone rubber(SIR)samples,and mass,electrical conductivity,and space charge were measured over a 96 h ageing period.The mass of the samples was found to exhibit nonmonotonic behaviour,indicating complex interactions between the lubricant and material.XLPE experiences a decrease in conductivity while there is an increase in conductivity for SIR,which is linked to the migration of lubricant and therefore changes in trap distribution.Space charge measurements indicate changes in trap characteristics,which depend strongly on the used type of lubricant.The findings highlight that lubricant diffusion affects both the bulk properties and charge accumulation at the interface,and underline the large effect of the type of lubricant.These results are crucial for understanding the long-term performance of cable joints and insulating materials in HVDC cable systems.展开更多
High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conduct...High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conducted and many achievements have been made in the study of theoretical issues of HVDC insulation,structural design and manufacture of HVDC cables with the corresponding accessories,as well as in condition monitoring technology.展开更多
To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃...To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃induced vibration response data of a three⁃span four⁃row double⁃layer cable PV support system.The wind⁃induced vibration characteristics with different PV module tilt angles,wind speeds,and wind direction angles were analyzed.The results showed that the double⁃layer cable large⁃span flexible PV support can effectively control the wind⁃induced vibration response and prevent the occur⁃rence of flutter under strong wind conditions.The maxi⁃mum value of the wind⁃induced vibration displacement of the flexible PV support system occurs in the windward first row.The upstream module has a significant shading effect on the downstream module,with a maximum effect of 23%.The most unfavorable wind direction angles of the structure are 0°and 180°.The change of the wind direction angle in the range of 0°to 30°has little effect on the wind vi⁃bration response.The change in the tilt angle of the PV modules has a greater impact on the wind vibration in the downwind direction and a smaller impact in the upwind di⁃rection.Special attention should be paid to the structural wind⁃resistant design of such systems in the upwind side span.展开更多
In the background of the construction of Sutong Yangtze River Bridge(short as Sutong Bridge),the cable construction method and techniques of a thousand-meter scale cable-stayed bridge are introduced.Some key construct...In the background of the construction of Sutong Yangtze River Bridge(short as Sutong Bridge),the cable construction method and techniques of a thousand-meter scale cable-stayed bridge are introduced.Some key construction techniques,such as outspreading cable on deck,installing cable at pylon,pulling and fixing cable at the attachment with decks and cable PE sheath protection are discussed.展开更多
Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of...Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.展开更多
The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control...The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.展开更多
In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential i...In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential issues with stress concentration and insufficient adaptability to the unique mechanical properties of loess,which may lead to challenges in ensuring long-term stability and effective reinforcement.Negative Poisson's ratio(NPR)anchor cables with constant resistance have emerged as a promising alternative,which can better match the engineering demands of loess slopes by providing more uniform stress distribution and adaptive deformation characteristics.The NPR cable's ability to maintain a constant resistance during deformation offers a distinct advantage over traditional methods as it can more effectively accommodate the complex and variable conditions of loess slopes.To investigate the anchoring performance of NPR cables in loess slope,the stress characteristics of NPR cable in loess medium were simulated and analysed by ABAQUS finite element software.First,static and general quasi-static analysis methods were used to simulate the NPR cable under static tensile conditions.The consistency of the simulated constant resistance deformation characteristics with experimental results found in the literature was verified.Second,the interaction model between the NPR cable coupled with the loess medium was established.Its constant resistance was calculated to be about 24.08%larger than that of NPR anchor cable while its plastic deformation was reduced by about 37.14%.The compressive stress on the contact surface between NPR cable and loess was concentrated near the free end of the sleeve,which indicated that the loess was prone to severe damage at the free end.The research results reveal the typical shear failure mechanism of NPR cable in loess medium,which provides an important theoretical basis for prevention of landslides and monitoring of loess slopes.展开更多
To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of...To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.展开更多
The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study...The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.展开更多
Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cy...Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cyclic loads.A finite element model is devised,incorporating a singular armor wire,a rigid core,and a damaged sheath.To scrutinize the buckling progression and corresponding deformation,axial compression and bending cyclic loads are introduced.The observations reveal that a reduction in axial compression results in a larger number of cycles before buckling ensues and progressively shifts the buckling position toward the extrados and fixed end.Decreasing the bending radius precipitates a reduction in the buckling cycle number and minimizes the deformation in the armor wire.Furthermore,an empirical model is presented to predict the occurrence of birdcage buckling,providing a means to anticipate buckling events and to estimate the requisite number of cycles leading to buckling.展开更多
Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts dur...Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts during cable degassing process still faces great challenges.This work develops an extra-low frequency(ELF)dielectric analysis method based on time-dependent polarisation current for non-destructive detection of byproducts in XLPE.The effects of single byproduct of acetophenone and cumyl alcohol on the ELF dielectric properties of XLPE are studied separately.The ELF associated static permittivity and the dielectric loss of XLPE rise as the content of the single byproduct increases,and theαrelaxation(10−4-10−3 Hz)andβrelaxation(10−3-10−2 Hz)of XLPE are observed.Ionisation of acetophenone occurs above electric field strength of 20 kV,whereas ionisation tends to saturate above 50 kV.The optimal field strength for ELF dielectric testing of XLPE is determined to be 20-50 kV.Furthermore,the degassing factor is proposed to accurately determine the removal of byproducts.Based on these,the non-destructive detection of degassing of XLPE cable is achieved.The proposed ELF dielectric analysis method enables the non-destructive detection of byproducts in cables,opening a new avenue for cable degassing effect evaluation.展开更多
As the most important large-scale communication infrastructure in the world today,submarine cable can profoundly reflect the global Internet communication pattern,and is of great significance for understanding the glo...As the most important large-scale communication infrastructure in the world today,submarine cable can profoundly reflect the global Internet communication pattern,and is of great significance for understanding the global digital divide.We used multi-scale and network analysis methods to depict the distribution pattern,network structure and spatio-temporal evolution of global submarine cables at the national and landing point scales,in order to analyze the current situation,challenges and main directions of global digital divide governance.Results show that:(1)spatial distribution of global submarine cables is unbalanced,the United States and Europe are the concentrated distribution areas of submarine cables and global information flow centers;(2)core connections of the global submarine cable network are only composed of a tiny minority of countries or regions or landing points,and have strong geographical proximity and clustered-type characteristic,noting that multitudinous landing points of developed countries are at the semi-periphery or even periphery of the network;(3)submarine cables can alleviate the global digital divide through the three paths of infrastructure universalization,digital ecosystem reconstruction and economic empowerment,and the global digital divide governance still faces the dilemma of the differences in digital strategy development and the lack of a governance system.However,due to the increasingly important position of cities in developing countries in the international communication pattern,the global digital divide problem is being alleviated.展开更多
文摘This study investigates the performance of high-strength cable bolts under impact loading conditions representative of rock bursts in underground environments.Although widely used,the dynamic behaviour of these cable bolts has received limited experimental attention,and their effectiveness in seismically active zones remains a subject of ongoing debate.To address this gap,a reverse pull-out test machine integrated with a drop hammer rig was employed.Tests were conducted on 70-t SUMO bulbed and non-bulbed cable bolts with encapsulation lengths of 300 and 450 mm,subjected to an impact energy of 14.52 k J.Results indicate that non-bulbed cables,despite showing lower initial peak loads(average 218 vs.328 k N for bulbed cables at 300 mm encapsulation),demonstrated superior energy absorption(average 11.26 vs.8.75 k J)and displacement capacity(average 48.40 vs.36.25 mm).Increasing the encapsulation length for bulbed cables led to a reduction in initial peak load but improved displacement and energy absorption.The dominant failure mechanism was debonding at the cable-grout interface,characterised by frictional sliding and cable rotation.These findings provide new insights into the energy dissipation mechanisms of cables and support the development of more resilient ground support systems for dynamically active conditions.
基金Shenzhen Science and Technology Program(Grant No.20220817171811004)(Grant No.RCBS20231211090816033)+4 种基金the Major Key Project of PCL,China under Grant PCL2025A13Longgang District,Shenzhen's"Ten-Action Plan"for Supporting Innovation Projects(Grant No.LGKCSDPT2024002,LGKCSDPT2024003,LGKCSDPT2024004)the"Zhiguo"Action of Guangxi Science and Technology Program(Grant No.ZG2503980003)Guangdong S&T Program under(Grant No.2025B0909040003)Guangdong Provincial Leading Talent Program(Grant No.2024TX08Z319).
文摘The main cable is the primary load-bearing component of a suspension bridge,continuously exposed to harsh environmental conditions,such as wind and rain,throughout the year.These adverse conditions contribute to varying degrees of degradation and damage to the main cable,necessitating regular inspections to prevent catastrophic failures.Traditional manual inspection methods not only suffer from low efficiency but also pose significant safety risks to personnel.To address these challenges and ensure the safe and effective inspection of suspension bridge main cables,this study introduces a novel cooperative climbing robot,designated as Main Cable Robot Version II(CCRobot-M-II),inspired by the locomotion of the inchworm.The robot employs an alternating opening and closing mechanism of four gripper sets,mimicking the inchworm's movement to achieve efficient crawling along the suspension bridge handrails.This paper provides a comprehensive analysis of the structural design,key components,and motion mechanisms of CCRobot-M-II.A detailed force analysis of the robot's crawling process is also presented,followed by the design of the control system and the development of an efficient motion control algorithm.Laboratory experiments demonstrate that the robot achieves a positional error of 00.64%during crawling,with a maximum average crawling speed of 7.6 m/min.Furthermore,the biomimetic design enables the robot to overcome obstacles up to 30 mm in height and possess the capability to handle suspension bridge cables with spans ranging from 740 to 1100 mm.Finally,CCRobot-M-II successfully conducted an inspection of the main cable on a suspension bridge,marking the world's first successful deployment of a climbing robot for main cable inspection on a suspension bridge.
基金funded by the National Key R&D Program of China,China(No.2024YFF0507903)the National Key Research and Development Program of China(Grant No.2024YFF0507904)the National Natural Science Foundation of China,China(Grant No.52379114).These supports are gratefully acknowledged.
文摘In-situ enlargement of super-large-span tunnels can intensify excavation-induced unloading in the surrounding rock,increasing deformation demand and failure risk during construction.This study combines laboratory model tests with FLAC3D simulations to evaluate the stabilizing role of prestressed anchor cables and to establish an energy-balance framework for support optimization.Comparative model tests of existing and enlarged tunnel sections,with and without anchors,show that reinforcement increases load-carrying capacity,reduces displacement,and confines damage to more localized zones.The numerical simulations reproduce displacement fields,shear-strain localization,and plastic-zone evolution with good agreement against the experimental observations.The energy framework is implemented in the in-situ simulations by quantifying unloading-related energy release in the rock mass and reinforcement work contributed by the anchors,and by introducing an energy release–reinforcement ratio as a stability indicator.Parametric analyses indicate that anchor length,spacing,and prestress influence stability in a nonlinear manner,with diminishing returns once reinforcement extends beyond the mechanically dominant deformation zone.An efficient parameter window is identified that improves deformation and yielding control while avoiding unnecessary reinforcement.The results provide an energy-consistent and design-oriented basis for prestressed anchorage selection in large-span tunnel expansion.
文摘This paper reviews the existing testing techniques for high voltage direct current(HVDC)cable systems,following as a backbone the structure of CIGRE Technical Brochure(TB)852:2021‘Recommendations for testing DC extruded cable systems for power transmission at a rated voltage up to 800 kV’because it has a fairly similar structure to CIGRE TB 853:2021 for lapped DC cables,and especially because of the impressive spread of HVDC extruded cables experienced worldwide in the last 25 years.The review considers development tests,pre-qualification tests,extension of qualification test,type tests(with hints at IEEE 1732-2017 for space charge measurements in the qualification of HVDC extruded cables),routine tests(with hints at IEEE 2862-2020 for routine tests of HVDC extruded cable system joints),sample tests and after installation tests.The review also analyses CIGRE TB 853 for lapped HVDC cable systems,as these cables remain unbeaten for submarine applications at the highest sea depths.The main novelties of CIGRE TB 852 and 853 with respect to previous standards for HVDC cable systems(mainly CIGRE TB 496 and IEC 62895 for extruded cables and CIGRE Electra 189:2000 for lapped cables)are put under the spotlight-with focus on the so-called temporary over-voltage tests-together with the limits and gaps of CIGRE TB 852.The main HVDC cable system testing equipment that is usually employed for electro-thermal tests is also treated.Emphasis is given to CIGRE TB 490 to treat the peculiarities of submarine cable systems,as well as to mechanical tests,having CIGRE TB 623 as a reference,with particular focus on the special sea trial tests.An example of an innovative sea trial testing procedure is shown,which is the outcome of a fruitful partnership between a cable manufacturer and the national Transmission System Operator in Italy.
基金supported by the National Natural Science Foundation of China(Grant Nos.42307189 and 42030701)the China Postdoctoral Science Foundation(Grant No.2023M740974).
文摘The actively heated fiber-optic(AHFO)technology has emerged as a frontier and hotspot in soil water content measurement,offering advantages such as easy installation,large-scale distributed measurement capability,and resistance to electromagnetic interference.However,current AHFO water content sensors fail to simultaneously achieve high precision,applicability for deep soil,and automated real-time monitoring,thereby limiting their development and application.Therefore,this study introduces a novel actively heated fiber Bragg grating(AH-FBG)cable.Laboratory tests were conducted to assess the heating uniformity of the AH-FBG cable and to establish the temperature characteristic value(T_(t))-soil water content(θ)calibration formula for water content measurement.Subsequently,AH-FBG cables were deployed for in situ soil water content monitoring in a test pit on the Loess Plateau.Through two-year monitoring data verified the accuracy of the AH-FBG cable and elucidated the spatiotemporal distribution of in situ loess water content.Laboratory results demonstrated superior heating uniformity of AHFBG cable,with a T_(t) standard deviation of approximately 0.3℃.In the field,the AH-FBG cable exhibited excellent performance in soil water content measurement,achieving a high accuracy of 0.023 cm^(3)/cm^(3).Further analysis revealed that the θ fluctuation predominantly occurred within a 10 m depth from the soil surface,with an overall upward trend over the two-year monitoring period;the response of shallow θ to precipitation was significant but exhibited increasing hysteresis with depth;frequent precipitation significantly enhanced water infiltration depth.This study provides technical guidance for highprecision,quasi-distributed,automated and real-time water content measurement of deep soil.
基金supported by the Innovation Foundation of National Commercial Aircraft Manufacturing Engineering Technology Research Center(No.COMAC-SFGS-2022-1877)in part by the National Natural Science Foundation of China(No.92048301)。
文摘Cabin cables,as critical components of an aircraft's electrical system,significantly impact the operational efficiency and safety of the aircraft.The existing cable segmentation methods in civil aviation cabins are limited,especially in automation,heavily dependent on large amounts of data and resources,lacking the flexibility to adapt to different scenarios.To address these challenges,this paper introduces a novel image segmentation model,CableSAM,specifically designed for automated segmentation of cabin cables.CableSAM improves segmentation efficiency and accuracy using knowledge distillation and employs a context ensemble strategy.It accurately segments cables in various scenarios with minimal input prompts.Comparative experiments on three cable datasets demonstrate that CableSAM surpasses other advanced cable segmentation methods in performance.
文摘Charge dynamics at interfaces in high voltage direct current(HVDC)cable joints consisting of cable,joint insulation and lubricant may have an impact on the overall joint reliability.Although interactions between different lubricants and the joint insulation have been studied in recent years,the effect of lubricant diffusion on the electrical properties and charge dynamics at interfaces remains unclear and is therefore investigated in this paper.Different lubricants were applied at the interface of crosslinked polyethylene(XLPE)and silicone rubber(SIR)samples,and mass,electrical conductivity,and space charge were measured over a 96 h ageing period.The mass of the samples was found to exhibit nonmonotonic behaviour,indicating complex interactions between the lubricant and material.XLPE experiences a decrease in conductivity while there is an increase in conductivity for SIR,which is linked to the migration of lubricant and therefore changes in trap distribution.Space charge measurements indicate changes in trap characteristics,which depend strongly on the used type of lubricant.The findings highlight that lubricant diffusion affects both the bulk properties and charge accumulation at the interface,and underline the large effect of the type of lubricant.These results are crucial for understanding the long-term performance of cable joints and insulating materials in HVDC cable systems.
文摘High-voltage direct current(HVDC)cables are growing rapidly all over the world due to the development of offshore wind power interconnections,cross-island power interconnections,etc.Extensive research has been conducted and many achievements have been made in the study of theoretical issues of HVDC insulation,structural design and manufacture of HVDC cables with the corresponding accessories,as well as in condition monitoring technology.
基金The National Natural Science Foundation of China(No.52338011).
文摘To investigate the wind⁃induced vibration re⁃sponse characteristics of multispan double⁃layer cable photo⁃voltaic(PV)support structures,wind tunnel tests using an aeroelastic model were carried out to obtain the wind⁃induced vibration response data of a three⁃span four⁃row double⁃layer cable PV support system.The wind⁃induced vibration characteristics with different PV module tilt angles,wind speeds,and wind direction angles were analyzed.The results showed that the double⁃layer cable large⁃span flexible PV support can effectively control the wind⁃induced vibration response and prevent the occur⁃rence of flutter under strong wind conditions.The maxi⁃mum value of the wind⁃induced vibration displacement of the flexible PV support system occurs in the windward first row.The upstream module has a significant shading effect on the downstream module,with a maximum effect of 23%.The most unfavorable wind direction angles of the structure are 0°and 180°.The change of the wind direction angle in the range of 0°to 30°has little effect on the wind vi⁃bration response.The change in the tilt angle of the PV modules has a greater impact on the wind vibration in the downwind direction and a smaller impact in the upwind di⁃rection.Special attention should be paid to the structural wind⁃resistant design of such systems in the upwind side span.
基金National Science and Technology Support Program of China(No.2006BAG04B02)
文摘In the background of the construction of Sutong Yangtze River Bridge(short as Sutong Bridge),the cable construction method and techniques of a thousand-meter scale cable-stayed bridge are introduced.Some key construction techniques,such as outspreading cable on deck,installing cable at pylon,pulling and fixing cable at the attachment with decks and cable PE sheath protection are discussed.
基金supported by the National Natural Science Foundation of China(12072136).
文摘Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.
基金financial support from the National Natural Science Foundation of China(Grant No.41941018).
文摘The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.
基金the State Key Laboratory of Deep Geotechnical Mechanics and Underground Engineering(SKLGDUEK2124)of China University of Mining and Technology(Beijing)for its support for this research。
文摘In the realm of slope monitoring and reinforcement,traditional prestressing anchor cables are extensively used.However,these conventional methods often face limitations when applied to loess slopes,such as potential issues with stress concentration and insufficient adaptability to the unique mechanical properties of loess,which may lead to challenges in ensuring long-term stability and effective reinforcement.Negative Poisson's ratio(NPR)anchor cables with constant resistance have emerged as a promising alternative,which can better match the engineering demands of loess slopes by providing more uniform stress distribution and adaptive deformation characteristics.The NPR cable's ability to maintain a constant resistance during deformation offers a distinct advantage over traditional methods as it can more effectively accommodate the complex and variable conditions of loess slopes.To investigate the anchoring performance of NPR cables in loess slope,the stress characteristics of NPR cable in loess medium were simulated and analysed by ABAQUS finite element software.First,static and general quasi-static analysis methods were used to simulate the NPR cable under static tensile conditions.The consistency of the simulated constant resistance deformation characteristics with experimental results found in the literature was verified.Second,the interaction model between the NPR cable coupled with the loess medium was established.Its constant resistance was calculated to be about 24.08%larger than that of NPR anchor cable while its plastic deformation was reduced by about 37.14%.The compressive stress on the contact surface between NPR cable and loess was concentrated near the free end of the sleeve,which indicated that the loess was prone to severe damage at the free end.The research results reveal the typical shear failure mechanism of NPR cable in loess medium,which provides an important theoretical basis for prevention of landslides and monitoring of loess slopes.
基金The National High Technology Research and Development Program of China (863Program) (No.2006AA04Z234)
文摘To inspect inner wires of the cylindrical cables on a cable-stayed bridge, a new bisected wheel-based cable climbing robot is designed. The simple structure and the moving mode are described and the static features of the robot are analyzed. A cable with a diameter of 139 mm is selected as an example to calculate the design parameters of the robot. For safety energysaving landing in the case of electrical system failure, an electric damper based on back electromotive force and a gas damper with a slider-crank mechanism are introduced to exhaust the energy generated by gravity when the robot is slipping down along the cables. A simplified mathematical model is analyzed and the landing velocity is simulated. For the present design, the robot can climb up a cable with diameters varying from 65 to 205 mm with payloads below 3.5 kg. Several climbing experiments performed on real cables confirm that the proposed robot meets the demands of inspection.
基金Financial supports for this work,provided by the National Natural Science Foundation Project of China(No.52374152)the Guangxi Science and Technology Plan Project of China(No.2022AB31023)the National Basic Research Development Program of China(No.2022YFC2904602)are gratefully acknowledged。
文摘The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.
基金financially supported by the National Natural Science Foundation of China(Grant No.52471301)the Fujian Province Transportation Science and Technology Project(Grant No.JC202302)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY24E090003).
文摘Buckling failure in submarine cables presents a prevalent challenge in ocean engineering.This work aims to explore the buckling behavior of umbilical cables with damaged sheaths subjected to compression and bending cyclic loads.A finite element model is devised,incorporating a singular armor wire,a rigid core,and a damaged sheath.To scrutinize the buckling progression and corresponding deformation,axial compression and bending cyclic loads are introduced.The observations reveal that a reduction in axial compression results in a larger number of cycles before buckling ensues and progressively shifts the buckling position toward the extrados and fixed end.Decreasing the bending radius precipitates a reduction in the buckling cycle number and minimizes the deformation in the armor wire.Furthermore,an empirical model is presented to predict the occurrence of birdcage buckling,providing a means to anticipate buckling events and to estimate the requisite number of cycles leading to buckling.
基金supported by Project of Science and Technology of State Grid Corporation of China(Grant 5500-202458116A-1-1-ZN).
文摘Cross-linking byproducts in the cross-linked polyethylene(XLPE)cable insulation material significantly affect the insulation properties of XLPE,and the non-destructive detection method for cross-linking byproducts during cable degassing process still faces great challenges.This work develops an extra-low frequency(ELF)dielectric analysis method based on time-dependent polarisation current for non-destructive detection of byproducts in XLPE.The effects of single byproduct of acetophenone and cumyl alcohol on the ELF dielectric properties of XLPE are studied separately.The ELF associated static permittivity and the dielectric loss of XLPE rise as the content of the single byproduct increases,and theαrelaxation(10−4-10−3 Hz)andβrelaxation(10−3-10−2 Hz)of XLPE are observed.Ionisation of acetophenone occurs above electric field strength of 20 kV,whereas ionisation tends to saturate above 50 kV.The optimal field strength for ELF dielectric testing of XLPE is determined to be 20-50 kV.Furthermore,the degassing factor is proposed to accurately determine the removal of byproducts.Based on these,the non-destructive detection of degassing of XLPE cable is achieved.The proposed ELF dielectric analysis method enables the non-destructive detection of byproducts in cables,opening a new avenue for cable degassing effect evaluation.
基金National Natural Science Foundation of China,No.42371175。
文摘As the most important large-scale communication infrastructure in the world today,submarine cable can profoundly reflect the global Internet communication pattern,and is of great significance for understanding the global digital divide.We used multi-scale and network analysis methods to depict the distribution pattern,network structure and spatio-temporal evolution of global submarine cables at the national and landing point scales,in order to analyze the current situation,challenges and main directions of global digital divide governance.Results show that:(1)spatial distribution of global submarine cables is unbalanced,the United States and Europe are the concentrated distribution areas of submarine cables and global information flow centers;(2)core connections of the global submarine cable network are only composed of a tiny minority of countries or regions or landing points,and have strong geographical proximity and clustered-type characteristic,noting that multitudinous landing points of developed countries are at the semi-periphery or even periphery of the network;(3)submarine cables can alleviate the global digital divide through the three paths of infrastructure universalization,digital ecosystem reconstruction and economic empowerment,and the global digital divide governance still faces the dilemma of the differences in digital strategy development and the lack of a governance system.However,due to the increasingly important position of cities in developing countries in the international communication pattern,the global digital divide problem is being alleviated.
