To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concret...To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.展开更多
Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively ap...Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively applied to analyze the initiation and propagation of the 2021 Chamoli avalancheinduced air blast.Our findings indicate that air blasts are observed from the avalanche source area to the Rishiganga valley,but nearly disappear in the Dhauliganga valley.The most intense air blast is concentrated on the left side of Ronti Gad valley,with maximum velocity and pressure estimated at over 70 m/s and 20 kPa,respectively.Such high pressure results in widespread tree breakage in the area.Based on the analysis of the Chamoli event,we further discussed the potential contribution of the avalanche flow regime,avalanche dynamics and geomorphology to the destructive potential of air blasts.Rapidly moved sliding mass can impart the air blast a high initial momentum,and this process will be exaggerated when the avalanche impacts valley walls at bends.However,when the rock-ice avalanche transforms into a debris-enriched flash flood,free water within the flowing mass can displace air,inhibiting the generation of air blasts.Our work offers new insights into the generation and propagation of rock-ice avalanche-induced air blasts,underscoring the importance of including this type of hazard during avalanche risk assessment in high-altitude glacial regions.展开更多
Unidirectional carbon/carbon（C/C） composites modified with in situ grown carbon nanofibers（CNFs） were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of...Unidirectional carbon/carbon（C/C） composites modified with in situ grown carbon nanofibers（CNFs） were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.展开更多
This paper analyzes the destructive effect of lawlessness on Dorian Gray in The Picture of Dorian Gray and Kurtz in Heart of Darkness.Under the protection of his portrait,Dorian Gray is lost in his seeking for pleasur...This paper analyzes the destructive effect of lawlessness on Dorian Gray in The Picture of Dorian Gray and Kurtz in Heart of Darkness.Under the protection of his portrait,Dorian Gray is lost in his seeking for pleasure and corrupts from a good angel into a vicious devil.As an oppressor in Africa,Kurtz can make his law and can do anything without punishment and is thus destroyed by his insatiable desire for ivory.The corruption of Dorian Gray and Kurtz shows that without observation,man may expose his evil side to an extreme.展开更多
This paper involves a series of destructive full-scale load tests on long bored piles instrumented with strain gauges along the shafts,including two compression and two tension loading tests.The load-displacement resp...This paper involves a series of destructive full-scale load tests on long bored piles instrumented with strain gauges along the shafts,including two compression and two tension loading tests.The load-displacement response,axial force,skin friction,and the thresholds of the slip displacement for fully mobilizing the skin resistances in different soils are discussed.Moreover,the theoretical solution for estimating the pile tip settlement under compression was adopted to analyze the test results.It was found that the measured skin frictions for the piles under compression were about 6% to 42% higher than the estimated values of the cone penetration tests(CPTs),whereas the measured skin frictions in the uplift cases were about 16% to 50% smaller than the estimated values.In addition,the average limited skin frictions for the tension piles were about 0.36 to 0.78 times the average ultimate skin frictions for the piles under compression.It also can be indicated that the skin friction along the pile depth approached the limited state,and decreased from a peak value with increasing loads.展开更多
Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly des...Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly desired in plenty of applications.In this paper,we propose a new design of metasurface with just one single layer dielectric structure to tune the reflection of an interface by destructive interference in a subwavelength scale.By arranging the orientation of nano-antennas,the reflectivity tuning from 20%to 90%can be achieved at the wavelength of 1550 nm.Moreover,such reflectivity tuning of the designed metasurface works at the tunable wavelength from1500 nm to 1600 nm.This ultra-thin solution can achieve similar performance as the traditional bulky components without diffraction orders,while the design and fabrication are much simple and flexible.The ultra-thin and tunable properties indicate the great potentials of this method to be applied in laser fabrication,optical communication and optical integration.展开更多
There are many methods to identify and recognize the molecular and behavioural differences between organisms.One of the methods for the detection and identification of unknown organisms as well as intermolecular and i...There are many methods to identify and recognize the molecular and behavioural differences between organisms.One of the methods for the detection and identification of unknown organisms as well as intermolecular and intramolecular structural differences is MALDI-TOF mass spectrometry.Therefore,differentiation of Fomes fomentarius decay capabilities on the chemical properties of the wood cell wall of the tree species Quercus castaneifolia,Juglans regia,and Carpinus betulus were used to determine and characterize the destructive behaviour of F.fomentarius decay by MALDI-TOF mass spectrometry.The results showed that the fungus had more significant destructive behaviour on J.regia than the other species.For this evidence,completely removal of xylan hemicellulose fragment+Na+at peak 1227 Da and severe digestion of fragment of glucomannan hemicellulose at peak 1477–1480 Da that it seems that signs of soft-rot patterns were obtained from the decayed sample of J.regia,while these were incremental and unchanged for C.betulus and Q.castaneifolia,respectively.However,C.betulus had different peaks of atomic mass than J.regia and Q.castaneifolia wood,respectively.These results showed that this technique could be useful for separating and identifying unknown compounds of the wood cell wall attacked by fungi relying on their biological behaviour.展开更多
文摘To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.
基金supported by the National Natural Science Foundation of China(Grant Nos.U2244227,42277126 and 41977215).
文摘Air blasts induced by rock-ice avalanches are common natural phenomena known for their far-field destructive impact.In this study,remote sensing images,eyewitness videos and numerical modelling were comprehensively applied to analyze the initiation and propagation of the 2021 Chamoli avalancheinduced air blast.Our findings indicate that air blasts are observed from the avalanche source area to the Rishiganga valley,but nearly disappear in the Dhauliganga valley.The most intense air blast is concentrated on the left side of Ronti Gad valley,with maximum velocity and pressure estimated at over 70 m/s and 20 kPa,respectively.Such high pressure results in widespread tree breakage in the area.Based on the analysis of the Chamoli event,we further discussed the potential contribution of the avalanche flow regime,avalanche dynamics and geomorphology to the destructive potential of air blasts.Rapidly moved sliding mass can impart the air blast a high initial momentum,and this process will be exaggerated when the avalanche impacts valley walls at bends.However,when the rock-ice avalanche transforms into a debris-enriched flash flood,free water within the flowing mass can displace air,inhibiting the generation of air blasts.Our work offers new insights into the generation and propagation of rock-ice avalanche-induced air blasts,underscoring the importance of including this type of hazard during avalanche risk assessment in high-altitude glacial regions.
基金Project(2011CB605804)supported by the National Basic Research Program of ChinaProject(51165006)supported by the National Natural Science Foundation of China+1 种基金Project(BY2013015-32)supported by Cooperative Innovation Fund-Prospective Project of Jiangsu Province,ChinaProject(JUSRP1045)supported by the Fundamental Research Funds for the Central Universities,China
文摘Unidirectional carbon/carbon（C/C） composites modified with in situ grown carbon nanofibers（CNFs） were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.
文摘This paper analyzes the destructive effect of lawlessness on Dorian Gray in The Picture of Dorian Gray and Kurtz in Heart of Darkness.Under the protection of his portrait,Dorian Gray is lost in his seeking for pleasure and corrupts from a good angel into a vicious devil.As an oppressor in Africa,Kurtz can make his law and can do anything without punishment and is thus destroyed by his insatiable desire for ivory.The corruption of Dorian Gray and Kurtz shows that without observation,man may expose his evil side to an extreme.
基金Project(No.51078330)supported by the National Natural Science Foundation of China
文摘This paper involves a series of destructive full-scale load tests on long bored piles instrumented with strain gauges along the shafts,including two compression and two tension loading tests.The load-displacement response,axial force,skin friction,and the thresholds of the slip displacement for fully mobilizing the skin resistances in different soils are discussed.Moreover,the theoretical solution for estimating the pile tip settlement under compression was adopted to analyze the test results.It was found that the measured skin frictions for the piles under compression were about 6% to 42% higher than the estimated values of the cone penetration tests(CPTs),whereas the measured skin frictions in the uplift cases were about 16% to 50% smaller than the estimated values.In addition,the average limited skin frictions for the tension piles were about 0.36 to 0.78 times the average ultimate skin frictions for the piles under compression.It also can be indicated that the skin friction along the pile depth approached the limited state,and decreased from a peak value with increasing loads.
基金financially supported by A*STAR, SERC 2014 Public Sector Research Funding (PSF) (Grant: SERC Project 1421200080)973 Program of China (2013CBA01700)+1 种基金Chinese Nature Science Grant (61675207)Mr.Li Yang acknowledges the support from China Scholarship Council (CSC)
文摘Reflection engineering plays an important role in optics.For conventional approaches,the reflection tuning is quite challenging in a loss-free component.Therefore,a simple approach to tune the reflection is highly desired in plenty of applications.In this paper,we propose a new design of metasurface with just one single layer dielectric structure to tune the reflection of an interface by destructive interference in a subwavelength scale.By arranging the orientation of nano-antennas,the reflectivity tuning from 20%to 90%can be achieved at the wavelength of 1550 nm.Moreover,such reflectivity tuning of the designed metasurface works at the tunable wavelength from1500 nm to 1600 nm.This ultra-thin solution can achieve similar performance as the traditional bulky components without diffraction orders,while the design and fabrication are much simple and flexible.The ultra-thin and tunable properties indicate the great potentials of this method to be applied in laser fabrication,optical communication and optical integration.
文摘There are many methods to identify and recognize the molecular and behavioural differences between organisms.One of the methods for the detection and identification of unknown organisms as well as intermolecular and intramolecular structural differences is MALDI-TOF mass spectrometry.Therefore,differentiation of Fomes fomentarius decay capabilities on the chemical properties of the wood cell wall of the tree species Quercus castaneifolia,Juglans regia,and Carpinus betulus were used to determine and characterize the destructive behaviour of F.fomentarius decay by MALDI-TOF mass spectrometry.The results showed that the fungus had more significant destructive behaviour on J.regia than the other species.For this evidence,completely removal of xylan hemicellulose fragment+Na+at peak 1227 Da and severe digestion of fragment of glucomannan hemicellulose at peak 1477–1480 Da that it seems that signs of soft-rot patterns were obtained from the decayed sample of J.regia,while these were incremental and unchanged for C.betulus and Q.castaneifolia,respectively.However,C.betulus had different peaks of atomic mass than J.regia and Q.castaneifolia wood,respectively.These results showed that this technique could be useful for separating and identifying unknown compounds of the wood cell wall attacked by fungi relying on their biological behaviour.
