The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ ass...The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.展开更多
A valid strategy to tailor the properties of polylactic acid for more extensive applications was introducing filler.In this work,basalt fiber assembled with in-situ SiO_(2) nanoparticles on the surface was successfull...A valid strategy to tailor the properties of polylactic acid for more extensive applications was introducing filler.In this work,basalt fiber assembled with in-situ SiO_(2) nanoparticles on the surface was successfully prepared via hydrothermal method and it was further treated with coupling agent KH-550 to improve interfacial interaction between polylactic acid(PLA)and basalt fibers(BF).It was demonstrated that the introduction of BFS could increase the crystallization of PLA and resulted in forming trans-crystallization based on TG and DSC results.The tensile strength of PLA/BF composites raised from 39 MPa to 62.5 MPa with increasing the fiber loading from 1 wt%to 10 wt%.Furthermore,the interfacial interaction could be effectively improved by assembling SiO_(2)(especially with 250 nm in diameter)on BF surface to build mechanical locking,which could keep the PLA matrix in place during the mechanical deformation with the tensile strength value raised from 62.5 MPa to 74.0 MPa.It is noticeable that the impact and flexural properties were effectively increased with the incorporation of in-situ SiO_(2) nanoparticles.The further KH-550 treatment made a positive impact as well.For instance,the impact strength and flexural strength of the sample with SiO_(2) and KH-550 modification were improved to 22.49 k J/m^(2) and 146.83 MPa and it enhanced about 42.16%and 41.04%than those of neat PLA,respectively.Therefore,an efficient enhancement of mechanical performance was achieved and this concept of assembling in-situ SiO_(2) on silica-based fiber as a modifier was a novel and simple path to design the interfacial construction and properties of the polymer composites.展开更多
Carbon nanotubes(CNTs)have generated remarkable interests in a wide range of research fields due to their excellent electri-cal properties.However,achieving the CNTs arrangement with high quality in a short time remai...Carbon nanotubes(CNTs)have generated remarkable interests in a wide range of research fields due to their excellent electri-cal properties.However,achieving the CNTs arrangement with high quality in a short time remains a challenge.Herein we studied the in-situ assembly of CNTs based on macroscopic dielectrophoresis by using a centimeter scale electrode,which overcome the limitation of small size in traditional method for manipulating nanoparticles.Ordered CNTs chains could be obtained under the action of alternating current dielectrophoresis by optimizing the voltage and frequency.Besides,the ordered chains were able to restore immediately upon powering up after being damaged.Furthermore,a CNTs chain was prepared for conducting the wet circuit and powering a LED,and different conductive patterns on the non-woven fabric were achieved by controlling the position of the electrodes in wet environment.展开更多
文摘The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.
基金funded by China Postdoctoral Science Foundation(No.2018M643699)the Xi’an Science and Technology Bureau Innovation Leading Projects(No.201805037YD15CG21(23))+2 种基金the Natural Science Foundation of Shaanxi Province(No.2019JQ741)the Science and Technology Bureau of Beilin District,Xi’an(No.GX2035)the Postdoctoral Science Foundation of Shaanxi Province(No.2018BSHEDZZ101)。
文摘A valid strategy to tailor the properties of polylactic acid for more extensive applications was introducing filler.In this work,basalt fiber assembled with in-situ SiO_(2) nanoparticles on the surface was successfully prepared via hydrothermal method and it was further treated with coupling agent KH-550 to improve interfacial interaction between polylactic acid(PLA)and basalt fibers(BF).It was demonstrated that the introduction of BFS could increase the crystallization of PLA and resulted in forming trans-crystallization based on TG and DSC results.The tensile strength of PLA/BF composites raised from 39 MPa to 62.5 MPa with increasing the fiber loading from 1 wt%to 10 wt%.Furthermore,the interfacial interaction could be effectively improved by assembling SiO_(2)(especially with 250 nm in diameter)on BF surface to build mechanical locking,which could keep the PLA matrix in place during the mechanical deformation with the tensile strength value raised from 62.5 MPa to 74.0 MPa.It is noticeable that the impact and flexural properties were effectively increased with the incorporation of in-situ SiO_(2) nanoparticles.The further KH-550 treatment made a positive impact as well.For instance,the impact strength and flexural strength of the sample with SiO_(2) and KH-550 modification were improved to 22.49 k J/m^(2) and 146.83 MPa and it enhanced about 42.16%and 41.04%than those of neat PLA,respectively.Therefore,an efficient enhancement of mechanical performance was achieved and this concept of assembling in-situ SiO_(2) on silica-based fiber as a modifier was a novel and simple path to design the interfacial construction and properties of the polymer composites.
基金support by the Fundamental Research Funds for the Central Universities(2232019A3-02)DHU Distinguished Young Professor Program(LZB2019002)+3 种基金Innovation Program of Shanghai Municipal Education Commission(2017-01-07-00-03-E00055)China Postdoctoral Science Foundation Grant(2019M651324)State Key Laboratory for Space Power Sources Technology(No.YF07050117F0768)Shanghai Industrial Technology Center of Graphene.
文摘Carbon nanotubes(CNTs)have generated remarkable interests in a wide range of research fields due to their excellent electri-cal properties.However,achieving the CNTs arrangement with high quality in a short time remains a challenge.Herein we studied the in-situ assembly of CNTs based on macroscopic dielectrophoresis by using a centimeter scale electrode,which overcome the limitation of small size in traditional method for manipulating nanoparticles.Ordered CNTs chains could be obtained under the action of alternating current dielectrophoresis by optimizing the voltage and frequency.Besides,the ordered chains were able to restore immediately upon powering up after being damaged.Furthermore,a CNTs chain was prepared for conducting the wet circuit and powering a LED,and different conductive patterns on the non-woven fabric were achieved by controlling the position of the electrodes in wet environment.
