A generalized nonlinear Baker failure criterion is employed with the upper bound limit analysis to study the surrounding rock stability of underground cavities. A three-dimensional(3D) failure mode is established by e...A generalized nonlinear Baker failure criterion is employed with the upper bound limit analysis to study the surrounding rock stability of underground cavities. A three-dimensional(3D) failure mode is established by extending the two-dimensional(2D) failure mode, which offers an upper bound expression of the surrounding rock pressure. This method is validated with a series of examples before the influence of four parameters of scale parameter, curvature parameter, shift parameter and lateral pressure coefficient, on the surrounding rock pressure is analyzed. According to these results, failure ranges of the underground cavities are determined. The following conclusions are reached:(1) the proposed approach is more accurate to predict surrounding rock pressure than the Mohr-Coulomb failure criterion;(2) the surrounding rock with large scale parameter, curvature parameter, shift parameter, and lateral pressure coefficient can lead to a more stable underground cavity;(3) the failure range in 3D mode can be predicted according to the upper bound solutions.展开更多
The linear stability analysis of the fiber suspension Taylor-Couette flow against axisymmetric and non-axisymmetric disturbances is investigated. A generalized complex eigenvalue problem generated from the linearized ...The linear stability analysis of the fiber suspension Taylor-Couette flow against axisymmetric and non-axisymmetric disturbances is investigated. A generalized complex eigenvalue problem generated from the linearized set of the three-dimensional governing system equations around the basic Couette azimuthal solution are solved numerically with the Chebyshev spectral method. In a wide range of radius ratios and the magnitudes of counter rotating, critical bifurcation thresholds from the axisymmetric Couette flow to the flow with different azimuthal wave numbers are obtained. The complex dispersion relations of the linearized stability equation system for vortex patterns with different azimuthal wave number are calculated for real axial wave numbers for axially extended vortex structures.展开更多
We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Gel...We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Geld for precalculated interaction times with everymode.展开更多
Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are d...Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are divided into micro-level and macro-level sequences. Individual and family systems are covered in the former sequence, while communities and organizations are the systems of focus in the latter sequence. The group system is often minimized and/or completely ignored in the process, even though there may be some reference made to groups in both practice methods sequences. Consequently, the mezzo-level system of groups is only given ＂lip-service＂ in the dyadic division of micro and macro-level practice. Furthermore, students often do not have the opportunity to practice in group settings, much less, develop competency in these professional venues. This paper describes a teaching format used in a BSW Program in an effort to ensure student competency as required in a Groups Practice course. The triangular model includes： （1） Classroom teaching of theory; （2） Practice of group dynamics; and （3） Supervision by instructors and MSW students.展开更多
基金Projects(51679117,11772358,51774322,51474249,51404179,51274249)supported by the National Natural Science Foundation of China。
文摘A generalized nonlinear Baker failure criterion is employed with the upper bound limit analysis to study the surrounding rock stability of underground cavities. A three-dimensional(3D) failure mode is established by extending the two-dimensional(2D) failure mode, which offers an upper bound expression of the surrounding rock pressure. This method is validated with a series of examples before the influence of four parameters of scale parameter, curvature parameter, shift parameter and lateral pressure coefficient, on the surrounding rock pressure is analyzed. According to these results, failure ranges of the underground cavities are determined. The following conclusions are reached:(1) the proposed approach is more accurate to predict surrounding rock pressure than the Mohr-Coulomb failure criterion;(2) the surrounding rock with large scale parameter, curvature parameter, shift parameter, and lateral pressure coefficient can lead to a more stable underground cavity;(3) the failure range in 3D mode can be predicted according to the upper bound solutions.
基金the Major Programof the National Natural Science Foundation of China with Grant No10632070
文摘The linear stability analysis of the fiber suspension Taylor-Couette flow against axisymmetric and non-axisymmetric disturbances is investigated. A generalized complex eigenvalue problem generated from the linearized set of the three-dimensional governing system equations around the basic Couette azimuthal solution are solved numerically with the Chebyshev spectral method. In a wide range of radius ratios and the magnitudes of counter rotating, critical bifurcation thresholds from the axisymmetric Couette flow to the flow with different azimuthal wave numbers are obtained. The complex dispersion relations of the linearized stability equation system for vortex patterns with different azimuthal wave number are calculated for real axial wave numbers for axially extended vortex structures.
文摘We present a scheme of preparing the tripartite W state among three cavitymodes of radiation field inside high-Q superconducting cavities. Our scheme is based on theinteraction of a four-level atom with the cavity Geld for precalculated interaction times with everymode.
文摘Social Work students typically enroll in the required practice methods courses that are specified by the Council on Social Work Education. At least in the majority of BSW Programs, these practice methods courses are divided into micro-level and macro-level sequences. Individual and family systems are covered in the former sequence, while communities and organizations are the systems of focus in the latter sequence. The group system is often minimized and/or completely ignored in the process, even though there may be some reference made to groups in both practice methods sequences. Consequently, the mezzo-level system of groups is only given ＂lip-service＂ in the dyadic division of micro and macro-level practice. Furthermore, students often do not have the opportunity to practice in group settings, much less, develop competency in these professional venues. This paper describes a teaching format used in a BSW Program in an effort to ensure student competency as required in a Groups Practice course. The triangular model includes： （1） Classroom teaching of theory; （2） Practice of group dynamics; and （3） Supervision by instructors and MSW students.
