The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction...The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement(CSA), ordinary Portland cement(OPC), and calcium sulfate(CS) to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength(UCS), splitting tensile strength(STS), and volume change of fiber-added expansive mixtures were determined at different time periods(i.e. the strengths on the 28 th day, and the volume changes on the 1 st, 7 th, 14 th, 21 st, and 28 th days). The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion.展开更多
In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon n...In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon nanofi-ber),i.e.,1)variation of conductive networksformed by CNFs;2)tunneling resistance changein neighboring CNFs and 3)piezoresistivity展开更多
The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of...The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.展开更多
Additive manufacturing based on liquid resin curing is one of the most promising methods to construct delicate structures.However,precision and speed are limited by the vertical adhesion of in situ cured resin at the ...Additive manufacturing based on liquid resin curing is one of the most promising methods to construct delicate structures.However,precision and speed are limited by the vertical adhesion of in situ cured resin at the curing interface.To overcome the unavoidable adhesion and to develop a general curing interface,we propose a slippery surface taking inspiration of the peristome surface of the pitcher plant.Such surface shows ultra-low adhesive energy at the curing interface due to the inhibition of the direct contact between the cured resin and the solid surface,which also increases the reflling speed of liquid resin.Tis ultra-low adhesive energy interface is efective for continuous 3D printing and provides insights into the physical mechanisms in reducing vertical solid-solid interfacial adhesion.展开更多
基金financial support from Natural Sciences and Engineering ResearchCouncil(NSERC)(NSERC EGP 501335-16) along with the donated CSA cement
文摘The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement(CSA), ordinary Portland cement(OPC), and calcium sulfate(CS) to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength(UCS), splitting tensile strength(STS), and volume change of fiber-added expansive mixtures were determined at different time periods(i.e. the strengths on the 28 th day, and the volume changes on the 1 st, 7 th, 14 th, 21 st, and 28 th days). The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion.
文摘In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon nanofi-ber),i.e.,1)variation of conductive networksformed by CNFs;2)tunneling resistance changein neighboring CNFs and 3)piezoresistivity
基金supported by the National Key R&D Program of China under Contract No.2022YFA1602200the International Partnership Program of the Chineses Academy of Sciences under Grant No.211134KYSB20200057the STCF Key Technology Research and Development Project.
文摘The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.
基金Te authors L.Wu,Z.Dong,C.Li,and Y.Song acknowledge the National Key R&D Program of China(Grant Nos.2018YFA0208501,2016YFB0401603,2016YFC1100502,and 2016YFB0401100)the NSFC(Grant Nos.51803219,51773206,51473172,51473173,and 21671193)+1 种基金and the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant No.XDA09020000)N.X.Fang and H.Du are grateful for the seed provided by the MIT Energy Initiative.
文摘Additive manufacturing based on liquid resin curing is one of the most promising methods to construct delicate structures.However,precision and speed are limited by the vertical adhesion of in situ cured resin at the curing interface.To overcome the unavoidable adhesion and to develop a general curing interface,we propose a slippery surface taking inspiration of the peristome surface of the pitcher plant.Such surface shows ultra-low adhesive energy at the curing interface due to the inhibition of the direct contact between the cured resin and the solid surface,which also increases the reflling speed of liquid resin.Tis ultra-low adhesive energy interface is efective for continuous 3D printing and provides insights into the physical mechanisms in reducing vertical solid-solid interfacial adhesion.
