Trapdoor stability has been widely studied by many researchers in the field of tunneling engineering.A general question being fre-quently asked is that why most sinkholes have a near-perfect circular shape on the grou...Trapdoor stability has been widely studied by many researchers in the field of tunneling engineering.A general question being fre-quently asked is that why most sinkholes have a near-perfect circular shape on the ground surface.This could be possibly explained by the current numerical study using finite element limit analysis under axisymmetric condition,where upper and lower bound solutions of active circular trapdoors are determined.The failure study of sinkholes and the associated failure mechanisms in this paper are for non-homogeneous clay with a linear increase of strength with depth under various cover depth ratios and dimensionless strength gra-dients.A design equation for predicting the stability solutions is also developed based on the novel three dimensional solutions using axisymmetry.展开更多
Attribute-Based Encryption (ABE) has been widely used for ciphertext retrieval in the cloud environment.However,bi-flexible attribute control and privacy keywords are difficult problems that have yet to be solved.In t...Attribute-Based Encryption (ABE) has been widely used for ciphertext retrieval in the cloud environment.However,bi-flexible attribute control and privacy keywords are difficult problems that have yet to be solved.In this paper,we introduce the denial of access policy and the mutual matching algorithm of a dataset used to realize bidirectional control of attributes in the cloud server.To solve the problem of keyword privacy,we construct a security trapdoor by adding random numbers that effectively resist keyword guessing attacks from cloud servers and external attackers.System security is reduced to the Deterministic Bilinear Diffie-Hellman (DBDH) hypothesis problem.We validate our scheme through theoretical security analysis and experimental verification.Experiments are conducted on a real dataset,and results show that the scheme has higher security and retrieval efficiency than previous methods.展开更多
Several environmental changes can induce an underground hole,leading to failures of non-ground infrastructure,such as pavements.Under a continued overload of traffic action on the pavement,the hole can potentially col...Several environmental changes can induce an underground hole,leading to failures of non-ground infrastructure,such as pavements.Under a continued overload of traffic action on the pavement,the hole can potentially collapse,leading to creation of potholes.This phenomenon is commonly known as a trapdoor problem.Even though there are several previous works considering this problem,the stability solutions of trapdoors in two-layered soils have not yet been studied.To estimate the undrained stability of active trapdoors in two-layered clays under plane strain conditions,numerical solutions based on the finite element method have been developed.The influence parameters include the coverage depth of the trapdoor,and the thickness and undrained shear strength of the clay layers.The effects of these parameters on the stability of active trapdoors as well as their associated failure mechanisms are examined and discussed in this paper.The solutions are presented in the form of dimensionless charts that can be used for the design of trapdoor systems in two-layered clays with different thicknesses and undrained shear strengths.展开更多
This study presents a hybrid framework to predict stability solutions of buried structures under active trapdoor conditions in natural clays with anisotropy and heterogeneity by combining physics-based and data-driven...This study presents a hybrid framework to predict stability solutions of buried structures under active trapdoor conditions in natural clays with anisotropy and heterogeneity by combining physics-based and data-driven modeling.Finite-element limit analysis(FELA)with a newly developed anisotropic undrained shear(AUS)failure criterion is used to identify the underlying active failure mechanisms as well as to develop a numerical(physics-based)database of stability numbers for both planar and circular trapdoors.Practical considerations are given for natural clays to three linearly increasing shear strengths in compression,extension,and direct simple shear in the AUS material model.The obtained numerical solutions are compared and validated with published solutions in the literature.A multivariate adaptive regression splines(MARS)algorithm is further utilized to learn the numerical solutions to act as fast FELA data-driven surrogates for stability evaluation.The current MARS-based modeling provides both relative importance index and accurate design equations that can be used with confidence by practitioners.展开更多
文摘Trapdoor stability has been widely studied by many researchers in the field of tunneling engineering.A general question being fre-quently asked is that why most sinkholes have a near-perfect circular shape on the ground surface.This could be possibly explained by the current numerical study using finite element limit analysis under axisymmetric condition,where upper and lower bound solutions of active circular trapdoors are determined.The failure study of sinkholes and the associated failure mechanisms in this paper are for non-homogeneous clay with a linear increase of strength with depth under various cover depth ratios and dimensionless strength gra-dients.A design equation for predicting the stability solutions is also developed based on the novel three dimensional solutions using axisymmetry.
文摘Attribute-Based Encryption (ABE) has been widely used for ciphertext retrieval in the cloud environment.However,bi-flexible attribute control and privacy keywords are difficult problems that have yet to be solved.In this paper,we introduce the denial of access policy and the mutual matching algorithm of a dataset used to realize bidirectional control of attributes in the cloud server.To solve the problem of keyword privacy,we construct a security trapdoor by adding random numbers that effectively resist keyword guessing attacks from cloud servers and external attackers.System security is reduced to the Deterministic Bilinear Diffie-Hellman (DBDH) hypothesis problem.We validate our scheme through theoretical security analysis and experimental verification.Experiments are conducted on a real dataset,and results show that the scheme has higher security and retrieval efficiency than previous methods.
基金supported by the Thailand Research Fund[Grant no.DBG-6180004]the Ratchadapisek Sompoch Endowment Fund(2020),Chulalongkorn University[763014 Climate Change and Disaster Management Cluster].
文摘Several environmental changes can induce an underground hole,leading to failures of non-ground infrastructure,such as pavements.Under a continued overload of traffic action on the pavement,the hole can potentially collapse,leading to creation of potholes.This phenomenon is commonly known as a trapdoor problem.Even though there are several previous works considering this problem,the stability solutions of trapdoors in two-layered soils have not yet been studied.To estimate the undrained stability of active trapdoors in two-layered clays under plane strain conditions,numerical solutions based on the finite element method have been developed.The influence parameters include the coverage depth of the trapdoor,and the thickness and undrained shear strength of the clay layers.The effects of these parameters on the stability of active trapdoors as well as their associated failure mechanisms are examined and discussed in this paper.The solutions are presented in the form of dimensionless charts that can be used for the design of trapdoor systems in two-layered clays with different thicknesses and undrained shear strengths.
基金the funding support provided by National Natural Science Foundation of China(Grant No.42177121)Thammasat University Research Unit in Structural and Foundation Engineering.
文摘This study presents a hybrid framework to predict stability solutions of buried structures under active trapdoor conditions in natural clays with anisotropy and heterogeneity by combining physics-based and data-driven modeling.Finite-element limit analysis(FELA)with a newly developed anisotropic undrained shear(AUS)failure criterion is used to identify the underlying active failure mechanisms as well as to develop a numerical(physics-based)database of stability numbers for both planar and circular trapdoors.Practical considerations are given for natural clays to three linearly increasing shear strengths in compression,extension,and direct simple shear in the AUS material model.The obtained numerical solutions are compared and validated with published solutions in the literature.A multivariate adaptive regression splines(MARS)algorithm is further utilized to learn the numerical solutions to act as fast FELA data-driven surrogates for stability evaluation.The current MARS-based modeling provides both relative importance index and accurate design equations that can be used with confidence by practitioners.
