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
Based on the results of conventional triaxial compression tests and triaxial compression creep tests on Xiangjiaba sandstone,the failure modes in short-term tests and creep tests,fractography of sandstone after creep ...Based on the results of conventional triaxial compression tests and triaxial compression creep tests on Xiangjiaba sandstone,the failure modes in short-term tests and creep tests,fractography of sandstone after creep failure,short-term and creep failure criterion are analyzed.In the short-term tests and creep tests,the sandstone samples fail in a mix mode consisting of shear failure in a single main plane and tensile failure.Confining pressure can restrict brittle failure and enhance the ductility of sandstone.In the creep tests,brittle fracture is reduced and plastic deformation can fully be developed compared to the condition of short-term tests.And the shear fracture surfaces are flat and they are covered by small particles as a result of friction.When confining pressure increases,particle size decreases while the degree of friction on shear plane increases.On the tensile failure plane,the tensile trace and direction of tearing could be clearly observed.There are obvious tearing steps on the tensile failure plane and tearing laminated structure on the front edge of tearing fracture.The same criterion can be used for the short-term and creep behavior,and the fitting effect using the MOGI criterion is better than the DRUCKER PRAGER criterion.The cohesion and friction angle calculated by the MOGI criterion are in good accordance with those calculated by the MOHR COULOMB criterion.展开更多
We introduce the three-mode entangled state and set up an experiment to generate it. Then we discuss the three-mode squeezing operator squeezed ｜p, X2, X3〉→μ^-3/2｜p/μ, X2/μ, X3/μ） and the optical implement to...We introduce the three-mode entangled state and set up an experiment to generate it. Then we discuss the three-mode squeezing operator squeezed ｜p, X2, X3〉→μ^-3/2｜p/μ, X2/μ, X3/μ） and the optical implement to realize such a squeezed state. We also reveal that c-number .asymmetric shrink transform in the three-mode entangled state, i.e. ｜p, X2,X3）→μ^-1/2｜p/μ, X2,X3）, maps onto a kind of one-sided three-mode squeezing operator {iλ （∑i^3=1 Pi） （∑i^3=1 Qi） -λ/2}. Using the technique of integration within an ordered product （IWOP） of operators, we derive their normally ordered forms and construct the corresponding squeezed states.展开更多
Considering the essential and influential role of centrifugal compressors in a wide range of industries makes most of engineers research and study on design and optimization of centrifugal compressors. Centrifugal com...Considering the essential and influential role of centrifugal compressors in a wide range of industries makes most of engineers research and study on design and optimization of centrifugal compressors. Centrifugal compressors are the key to part ofoil, gas and petrochemical industries as well as gas pipeline transports. Since complete 3D design of the compressor consumes a considerable amount of time, most of active companies in the field, are profoundly interested in obtaining a design outline before taking any further steps in designing the entire machine. In this paper, a numerical algorithm, named ACDA （adapted compressor design algorithm） for fast and accurate preliminary design of centrifugal compressor is presented. The design procedure is obtained under real gas behavior, using an appropriate equation of state. Starting from impeller inlet, the procedure is continued on by resulting in numerical calculation for other sections including impeller exit, volute and exit diffuser. Clearly, in any step suitable correction factors are employed in order to conclude in precise numerical results. Finally, the achieved design result is compared with available reference data.展开更多
The S2 flow path design method of the transonic compressor is used to design the one stage fan in order to replace the original designed blade cascade which has two-stage transonic fan rotors.In the modification desig...The S2 flow path design method of the transonic compressor is used to design the one stage fan in order to replace the original designed blade cascade which has two-stage transonic fan rotors.In the modification design,the camber line is parameterized by a quartic polynomial curve and the thickness distribution of the blade profile is controlled by the double-thrice polynomial.Therefore,the inlet flow has been pre-compressed and the location and intensity of the shock wave at supersonic area have been controlled in order to let the new blade profiles have better aerodynamic performance.The computational results show that the new single stage fan rotor increases the efficiency by two percent at the design condition and the total pressure ratio is slightly higher than that of the original design.At the same time,it also meets the mass flow rate and the geometrical size requirements for the modification design.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Project(2011CB013504)supported by National Basic Research Program of ChinaProjects(51109069,11172090)supported by the National Natural Science Foundation of China+1 种基金Project(2009B14014)supported by the Fundamental Research Funds for the Central Universities of ChinaProject Financially supported by the Program for Changjiang Scholars and lnnovative Research Team in University,China
文摘Based on the results of conventional triaxial compression tests and triaxial compression creep tests on Xiangjiaba sandstone,the failure modes in short-term tests and creep tests,fractography of sandstone after creep failure,short-term and creep failure criterion are analyzed.In the short-term tests and creep tests,the sandstone samples fail in a mix mode consisting of shear failure in a single main plane and tensile failure.Confining pressure can restrict brittle failure and enhance the ductility of sandstone.In the creep tests,brittle fracture is reduced and plastic deformation can fully be developed compared to the condition of short-term tests.And the shear fracture surfaces are flat and they are covered by small particles as a result of friction.When confining pressure increases,particle size decreases while the degree of friction on shear plane increases.On the tensile failure plane,the tensile trace and direction of tearing could be clearly observed.There are obvious tearing steps on the tensile failure plane and tearing laminated structure on the front edge of tearing fracture.The same criterion can be used for the short-term and creep behavior,and the fitting effect using the MOGI criterion is better than the DRUCKER PRAGER criterion.The cohesion and friction angle calculated by the MOGI criterion are in good accordance with those calculated by the MOHR COULOMB criterion.
基金Open Foundation of Laboratory of High- Intensity Optics
文摘We introduce the three-mode entangled state and set up an experiment to generate it. Then we discuss the three-mode squeezing operator squeezed ｜p, X2, X3〉→μ^-3/2｜p/μ, X2/μ, X3/μ） and the optical implement to realize such a squeezed state. We also reveal that c-number .asymmetric shrink transform in the three-mode entangled state, i.e. ｜p, X2,X3）→μ^-1/2｜p/μ, X2,X3）, maps onto a kind of one-sided three-mode squeezing operator {iλ （∑i^3=1 Pi） （∑i^3=1 Qi） -λ/2}. Using the technique of integration within an ordered product （IWOP） of operators, we derive their normally ordered forms and construct the corresponding squeezed states.
文摘Considering the essential and influential role of centrifugal compressors in a wide range of industries makes most of engineers research and study on design and optimization of centrifugal compressors. Centrifugal compressors are the key to part ofoil, gas and petrochemical industries as well as gas pipeline transports. Since complete 3D design of the compressor consumes a considerable amount of time, most of active companies in the field, are profoundly interested in obtaining a design outline before taking any further steps in designing the entire machine. In this paper, a numerical algorithm, named ACDA （adapted compressor design algorithm） for fast and accurate preliminary design of centrifugal compressor is presented. The design procedure is obtained under real gas behavior, using an appropriate equation of state. Starting from impeller inlet, the procedure is continued on by resulting in numerical calculation for other sections including impeller exit, volute and exit diffuser. Clearly, in any step suitable correction factors are employed in order to conclude in precise numerical results. Finally, the achieved design result is compared with available reference data.
基金support from National Natural Science Foundation of China (Grant No.50706009)
文摘The S2 flow path design method of the transonic compressor is used to design the one stage fan in order to replace the original designed blade cascade which has two-stage transonic fan rotors.In the modification design,the camber line is parameterized by a quartic polynomial curve and the thickness distribution of the blade profile is controlled by the double-thrice polynomial.Therefore,the inlet flow has been pre-compressed and the location and intensity of the shock wave at supersonic area have been controlled in order to let the new blade profiles have better aerodynamic performance.The computational results show that the new single stage fan rotor increases the efficiency by two percent at the design condition and the total pressure ratio is slightly higher than that of the original design.At the same time,it also meets the mass flow rate and the geometrical size requirements for the modification design.
