Slope stability analysis is a classical mechanical problem in geotechnical engineering and engineering geology.It is of great significance to study the stability evolution of expansive soil slopes for engineering cons...Slope stability analysis is a classical mechanical problem in geotechnical engineering and engineering geology.It is of great significance to study the stability evolution of expansive soil slopes for engineering construction in expansive soil areas.Most of the existing studies evaluate the slope stability by analyzing the limit equilibrium state of the slope,and the analysis method for the stability evolution considering the damage softening of the shear zone is lacking.In this study,the large deformation shear mechanical behavior of expansive soil was investigated by ring shear test.The damage softening characteristic of expansive soil in the shear zone was analyzed,and a shear damage model reflecting the damage softening behavior of expansive soil was derived based on the damage theory.Finally,by skillfully combining the vector sum method and the shear damage model,an analysis method for the stability evolution of the expansive soil slope considering the shear zone damage softening was proposed.The results show that the shear zone subjected to large displacement shear deformation exhibits an obvious damage softening phenomenon.The damage variable equation based on the logistic function can be well used to describe the shear damage characteristics of expansive soil,and the proposed shear damage model is in good agreement with the ring shear test results.The vector sum method considering the damage softening behavior of the shear zone can be well applied to analyze the stability evolution characteristics of the expansive soil slope.The stability factor of the expansive soil slope decreases with the increase of shear displacement,showing an obvious progressive failure behavior.展开更多
The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method （DFEM）. Combining with the DFEM, the vector sum analysis method （VSAM） is...The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method （DFEM）. Combining with the DFEM, the vector sum analysis method （VSAM） is employed in seismic stability analysis of a slope in this paper. Different from other conventional methods, the VSAM is proposed based on the vector characteristic of force and current stress state of the slope. The dynamic stress state of the slope at any moment under seismic load can he obtained by the DFEM, thus the factor of safety of the slope at any moment during earthquake can be easily obtained with the VSAM in consideration of the DFEM. Then, the global stability of the slope can be estimated on the basis of time-history curve of factor of safety and reliability theory. The VSAM is applied to a homogeneous slope under seismic load. The factor of safety of the slope is 1.30 under gravity only and the dynamic factor of safety under seismic load is 1.21. The calculating results show that the dynamic characteristics and stability state of the slope with input ground motion can be actually analyzed. It is believed that the VSAM is a feasible and practical approach to estimate the dynamic stability of slopes under seismic load.展开更多
This paper presents a 5-bit active LO phase shifter with a new vector sum method for 9–12 GHz applications. The 5-bit phase shifter is composed of four 3-bit sub phase shifters by adopting the new vector sum method, ...This paper presents a 5-bit active LO phase shifter with a new vector sum method for 9–12 GHz applications. The 5-bit phase shifter is composed of four 3-bit sub phase shifters by adopting the new vector sum method, which reduces the requirements on the resolution of the variable gain amplifier（VGA）. The variable gain function is realized by switch on/off parallel input transistor pairs rather than changing the bias current of the VGA,which avoids the linearity variation and drain-source voltage variation existing in the quadrature vector sum active phase shifter. The 5-bit active LO phase shifter is fabricated in TSMC 0.13μm CMOS technology. The measured results show that the phase shifter achieves 5-bit phase shift accuracy. The average conversion gain for 32 phase states is 0：5 to 7 d B from 9 to 12 GHz. The RMS gain error and the RMS phase error are smaller than 0.8 d B and 4° respectively. The current consumption is 27.7 m A from a 1.2 V supply voltage.展开更多
This paper proposes a novel hypersphere support vector machines （HSVMs） based on generalized multiplicative updates. This algorithm can obtain the boundary of hypersphere containing one class of samples by the descr...This paper proposes a novel hypersphere support vector machines （HSVMs） based on generalized multiplicative updates. This algorithm can obtain the boundary of hypersphere containing one class of samples by the description of the training samples from one class and use this boundary to classify the test samples. The generalized multiplicative updates are applied to solving boundary optimization progranmning. Multiplicative updates available are suited for nonnegative quadratic convex programming. The generalized multiplicative updates are derived to box and sum constrained quadratic programming in this paper. They provide an extremely straightforward way to implement support vector machines （SVMs） where all variables are updated in parallel. The generalized multiplicative updates converge monotonically to the solution of the maximum margin hyperplane. The experiments show the superiority of our new algorithm.展开更多
Hanson-Wright inequality provides a powerful tool for bounding the norm ||ζ|| of a centered stochastic vector ζ with independent entries and sub-gaussian behavior.This paper extends the bounds to the case when ζ on...Hanson-Wright inequality provides a powerful tool for bounding the norm ||ζ|| of a centered stochastic vector ζ with independent entries and sub-gaussian behavior.This paper extends the bounds to the case when ζ only has bounded exponential moments of the form log E exp<V^(-1)ζ,u>≤||u||^(2)/2,where V^(2)≥Var(ζ)and ||u||≤g for some fixed g.For a linear mapping Q,we present an upper quantile function z_(c)(B,x)ensuring P(||Qζ||>z_(c)(B,x))≤3e^(-x) with B=QV^(2)Q^(T).The obtained results exhibit a phase transition effect:with a value Cc depending on g and B,for x≤x_(c),the function z_(c)(B,x)replicates the case of a Gaussian vector ζ,that is,z_(c)^(2)(B,x)=tr(B)+2√xtr(B_(2))+2x||B||.For x>x_(c),the function z_(c)(B,x)grows linearly in.The results are specified to the case of Bernoulli vector sums and to covariance estimation in Frobenius norm.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2019YFC1509901).
文摘Slope stability analysis is a classical mechanical problem in geotechnical engineering and engineering geology.It is of great significance to study the stability evolution of expansive soil slopes for engineering construction in expansive soil areas.Most of the existing studies evaluate the slope stability by analyzing the limit equilibrium state of the slope,and the analysis method for the stability evolution considering the damage softening of the shear zone is lacking.In this study,the large deformation shear mechanical behavior of expansive soil was investigated by ring shear test.The damage softening characteristic of expansive soil in the shear zone was analyzed,and a shear damage model reflecting the damage softening behavior of expansive soil was derived based on the damage theory.Finally,by skillfully combining the vector sum method and the shear damage model,an analysis method for the stability evolution of the expansive soil slope considering the shear zone damage softening was proposed.The results show that the shear zone subjected to large displacement shear deformation exhibits an obvious damage softening phenomenon.The damage variable equation based on the logistic function can be well used to describe the shear damage characteristics of expansive soil,and the proposed shear damage model is in good agreement with the ring shear test results.The vector sum method considering the damage softening behavior of the shear zone can be well applied to analyze the stability evolution characteristics of the expansive soil slope.The stability factor of the expansive soil slope decreases with the increase of shear displacement,showing an obvious progressive failure behavior.
基金Supported by the Program of Yunnan Provincial Institute of Communications Planning,Design and Research (2011(D)11-b)
文摘The vibration characteristics and dynamic responses of rock and soil under seismic load can be estimated with dynamic finite element method （DFEM）. Combining with the DFEM, the vector sum analysis method （VSAM） is employed in seismic stability analysis of a slope in this paper. Different from other conventional methods, the VSAM is proposed based on the vector characteristic of force and current stress state of the slope. The dynamic stress state of the slope at any moment under seismic load can he obtained by the DFEM, thus the factor of safety of the slope at any moment during earthquake can be easily obtained with the VSAM in consideration of the DFEM. Then, the global stability of the slope can be estimated on the basis of time-history curve of factor of safety and reliability theory. The VSAM is applied to a homogeneous slope under seismic load. The factor of safety of the slope is 1.30 under gravity only and the dynamic factor of safety under seismic load is 1.21. The calculating results show that the dynamic characteristics and stability state of the slope with input ground motion can be actually analyzed. It is believed that the VSAM is a feasible and practical approach to estimate the dynamic stability of slopes under seismic load.
基金Project supported by the National Natural Science Foundation of China(No.61376037)the National Twelve-Five Project(No.513***)
文摘This paper presents a 5-bit active LO phase shifter with a new vector sum method for 9–12 GHz applications. The 5-bit phase shifter is composed of four 3-bit sub phase shifters by adopting the new vector sum method, which reduces the requirements on the resolution of the variable gain amplifier（VGA）. The variable gain function is realized by switch on/off parallel input transistor pairs rather than changing the bias current of the VGA,which avoids the linearity variation and drain-source voltage variation existing in the quadrature vector sum active phase shifter. The 5-bit active LO phase shifter is fabricated in TSMC 0.13μm CMOS technology. The measured results show that the phase shifter achieves 5-bit phase shift accuracy. The average conversion gain for 32 phase states is 0：5 to 7 d B from 9 to 12 GHz. The RMS gain error and the RMS phase error are smaller than 0.8 d B and 4° respectively. The current consumption is 27.7 m A from a 1.2 V supply voltage.
基金Project supported by the National Natural Science Foundation of China (Grant No.60574075)
文摘This paper proposes a novel hypersphere support vector machines （HSVMs） based on generalized multiplicative updates. This algorithm can obtain the boundary of hypersphere containing one class of samples by the description of the training samples from one class and use this boundary to classify the test samples. The generalized multiplicative updates are applied to solving boundary optimization progranmning. Multiplicative updates available are suited for nonnegative quadratic convex programming. The generalized multiplicative updates are derived to box and sum constrained quadratic programming in this paper. They provide an extremely straightforward way to implement support vector machines （SVMs） where all variables are updated in parallel. The generalized multiplicative updates converge monotonically to the solution of the maximum margin hyperplane. The experiments show the superiority of our new algorithm.
基金Financial support by the German Research Foundation(DFG)through the Collaborative Research Center 1294"Data assimnilation"is gratefully acknowledged.
文摘Hanson-Wright inequality provides a powerful tool for bounding the norm ||ζ|| of a centered stochastic vector ζ with independent entries and sub-gaussian behavior.This paper extends the bounds to the case when ζ only has bounded exponential moments of the form log E exp<V^(-1)ζ,u>≤||u||^(2)/2,where V^(2)≥Var(ζ)and ||u||≤g for some fixed g.For a linear mapping Q,we present an upper quantile function z_(c)(B,x)ensuring P(||Qζ||>z_(c)(B,x))≤3e^(-x) with B=QV^(2)Q^(T).The obtained results exhibit a phase transition effect:with a value Cc depending on g and B,for x≤x_(c),the function z_(c)(B,x)replicates the case of a Gaussian vector ζ,that is,z_(c)^(2)(B,x)=tr(B)+2√xtr(B_(2))+2x||B||.For x>x_(c),the function z_(c)(B,x)grows linearly in.The results are specified to the case of Bernoulli vector sums and to covariance estimation in Frobenius norm.
