In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electr...In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electroslag re-melting process. Studies were carried out to investigate the microscopic and macroscopic effects of electrode immersion depth and melting rate on the potential distribution and heat density in the slag bath, and on the depth and shape of the molten bath. Based on the finite element method and the numerical solution method, the effect of the electrode immersion depth on the slag bath heat density was researched; the relationship between the electrode immersion depth and the slag resistance was obtained; and the unsteady-state model of the solidification process of the re-melting ingot was solved using the finite difference method. The mathematical model and physical model of the electrode melting process were established and solved; and the corresponding curves between the electrode molten-state and slag-bath physical parameters were obtained. The experimental results verified the simulated results studied in this paper.展开更多
A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedbac...A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedback gains is given. Moreover, a diffeomorphic structure between the set of stabilizing time-variant state feedback gains and the Cartesian product of positive definite matrix and skew symmetric matrix satisfying certain algebraic conditions is constructed. Furthermore, an immersion and some results about the eigenvalue locations of stable state feedback systems are derived.展开更多
The immersed tunnel is considered an effective solution for traffic problems across rivers and seas.The sand filling layer,as an important part of immersed tunnel foundation treatments,directly affects segment attitud...The immersed tunnel is considered an effective solution for traffic problems across rivers and seas.The sand filling layer,as an important part of immersed tunnel foundation treatments,directly affects segment attitude stability.Due to difficulties in quality control of concealed construction and the complex hydrodynamic environment,the sand filling layer is prone to compaction defects,further leading to changes in segment attitude.However,limited by structural concealment and state complexity,most studies consider the sand filling layer part of the foundation to study its impact on settlement while neglecting its influence on segment attitude.This research proposes an evaluation method for the sand filling layer state based on elastic wave testing and the elastic wave characteristic parameters selected come from analysis of the time domain,frequency domain and time–frequency domain.By classifying the elastic wave characteristic parameters through the K-means clustering method,the relationship between the state of the sand filling layer and the elastic wave characteristic parameters is established.The state of the sand filling layer is divided into dense,incompact,and void.A numerical model is established based on the Guangzhou BI-UT immersed tunnel with incompact and void sand filling layer states to simulate deformation and torsion.The results indicate that the settlement of the tunnel segment is low in the eastern region and high in the western region due to the presence of a less dense sand filling layer,with a maximum differential settlement of 0.04 m.The evaluation method plays a crucial role in guiding the construction of immersed tube tunnels.展开更多
基金financially supported by the Machine Tools Major Project of the Eleventh Five-Year Plan of China(grant No.2009ZX04006-032)
文摘In the electroslag remelting process, the electrode molten state is a critical factor determining the ingot quality, while the electrode immersion depth and melting rate are key factors for the stability of the electroslag re-melting process. Studies were carried out to investigate the microscopic and macroscopic effects of electrode immersion depth and melting rate on the potential distribution and heat density in the slag bath, and on the depth and shape of the molten bath. Based on the finite element method and the numerical solution method, the effect of the electrode immersion depth on the slag bath heat density was researched; the relationship between the electrode immersion depth and the slag resistance was obtained; and the unsteady-state model of the solidification process of the re-melting ingot was solved using the finite difference method. The mathematical model and physical model of the electrode melting process were established and solved; and the corresponding curves between the electrode molten-state and slag-bath physical parameters were obtained. The experimental results verified the simulated results studied in this paper.
文摘A new technique for considering the stabilizing time-variant state feedback gains is proposed from the viewpoint of information geometry. First, parametrization of the set of all stabilizing time-variant state feedback gains is given. Moreover, a diffeomorphic structure between the set of stabilizing time-variant state feedback gains and the Cartesian product of positive definite matrix and skew symmetric matrix satisfying certain algebraic conditions is constructed. Furthermore, an immersion and some results about the eigenvalue locations of stable state feedback systems are derived.
基金supported by Yunnan Province Major Science and Technology Special Plan(Grant No.202303AA080010)the National Natural Science Foundation of China(Grant No.52122110)+1 种基金the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University,China(Grant No.SL2021PT302)Academician Special Program of China Communications Construction Company(CCCC).
文摘The immersed tunnel is considered an effective solution for traffic problems across rivers and seas.The sand filling layer,as an important part of immersed tunnel foundation treatments,directly affects segment attitude stability.Due to difficulties in quality control of concealed construction and the complex hydrodynamic environment,the sand filling layer is prone to compaction defects,further leading to changes in segment attitude.However,limited by structural concealment and state complexity,most studies consider the sand filling layer part of the foundation to study its impact on settlement while neglecting its influence on segment attitude.This research proposes an evaluation method for the sand filling layer state based on elastic wave testing and the elastic wave characteristic parameters selected come from analysis of the time domain,frequency domain and time–frequency domain.By classifying the elastic wave characteristic parameters through the K-means clustering method,the relationship between the state of the sand filling layer and the elastic wave characteristic parameters is established.The state of the sand filling layer is divided into dense,incompact,and void.A numerical model is established based on the Guangzhou BI-UT immersed tunnel with incompact and void sand filling layer states to simulate deformation and torsion.The results indicate that the settlement of the tunnel segment is low in the eastern region and high in the western region due to the presence of a less dense sand filling layer,with a maximum differential settlement of 0.04 m.The evaluation method plays a crucial role in guiding the construction of immersed tube tunnels.
