Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects...Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.展开更多
In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation betw...In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications.展开更多
Because of the contents of spatial analysis were a wide range and are very complicated, there hasn’t been any unified theory system about it. In this paper, authors studied thedefinition and contents of spatial analy...Because of the contents of spatial analysis were a wide range and are very complicated, there hasn’t been any unified theory system about it. In this paper, authors studied thedefinition and contents of spatial analysis. From the view point of the simulation of the geographical space, the authors defines spatial analysis as a system that describes the special relationship and spatial action of the objects in the geographical space. Furthermore, the contentsof spatial analysis to spatial query, spatial interaction analysis and spatial decision supportwere extended.展开更多
With the high-tech industrialization of earth observation satellite remote sensing and the implementation of digital earth strategy,the energy and natural resources have been decided to be the key research fields in C...With the high-tech industrialization of earth observation satellite remote sensing and the implementation of digital earth strategy,the energy and natural resources have been decided to be the key research fields in China.In these fields,from the model based on topology data,through simple feature data model to rule-based data model,the basic spatial analysis algorithms have been developed展开更多
Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and...Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling en＇ors than that of the SOS-RARE from the resolution point of view.展开更多
基金Projects(52278395,52208409) supported by the National Natural Science Foundation of ChinaProject(2022JJ40531) supported by the Natural Science Foundation of Hunan Province,China。
文摘Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.
文摘In order to improve the detection accuracy of Doppler asymmetric spatial heterodyne(DASH)interferometer in harsh temperatures,an opto-mechanical-thermal integration analysis is carried out.Firstly,the correlation between the interference phase and temperature is established according to the working principle and the phase algorithm of the interferometer.Secondly,the optical mechanical thermal analysis model and thermal deformation data acquisition model are designed.The deformation data of the interference module and the imaging optical system at different temperatures are given by temperature load simulation analysis,and the phase error caused by thermal deformation is obtained by fitting.Finally,based on the wind speed error caused by thermal deformation of each component,a reasonable temperature control scheme is proposed.The results show that the interference module occupies the main cause,the temperature must be controlled within(20±0.05)℃,and the temperature control should be carried out for the temperature sensitive parts,and the wind speed error caused by the part is 3.8 m/s.The thermal drift between the magnification of the imaging optical system and the thermal drift of the relative position between the imaging optical system and the detector should occupy the secondary cause,which should be controlled within(20±2)℃,and the wind speed error caused by the part is 3.05 m/s.In summary,the wind measurement error caused by interference module,imaging optical system,and the relative position between the imaging optical system and the detector can be controlled within 6.85 m/s.The analysis and temperature control schemes presented in this paper can provide theoretical basis for DASH interferometer engineering applications.
文摘Because of the contents of spatial analysis were a wide range and are very complicated, there hasn’t been any unified theory system about it. In this paper, authors studied thedefinition and contents of spatial analysis. From the view point of the simulation of the geographical space, the authors defines spatial analysis as a system that describes the special relationship and spatial action of the objects in the geographical space. Furthermore, the contentsof spatial analysis to spatial query, spatial interaction analysis and spatial decision supportwere extended.
文摘With the high-tech industrialization of earth observation satellite remote sensing and the implementation of digital earth strategy,the energy and natural resources have been decided to be the key research fields in China.In these fields,from the model based on topology data,through simple feature data model to rule-based data model,the basic spatial analysis algorithms have been developed
基金Project(61201381)supported by the National Nature Science Foundation of ChinaProject(YP12JJ202057)supported by the Future Development Foundation of Zhengzhou Information Science and Technology College,China
文摘Compared to the rank reduction estimator （RARE） based on second-order statistics （called SOS-RARE）, the RARE employing fourth-order cumulants （referred to as FOC-RARE） is capable of dealing with more sources and mitigating the negative influences of the Gaussian colored noise. However, in the presence of unexpected modeling errors, the resolution behavior of the FOC-RARE also deteriorate significantly as SOS-RARE, even for a known array covariance matrix. For this reason, the angle resolution capability of the FOC-RARE was theoretically analyzed. Firstly, the explicit formula for the mathematical expectation of the FOC-RARE spatial spectrum was derived through the second-order perturbation analysis method. Then, with the assumption that the unexpected modeling errors were drawn from complex circular Gaussian distribution, the theoretical formulas for the angle resolution probability of the FOC-RARE were presented. Numerical experiments validate our analytical results and demonstrate that the FOC-RARE has higher robustness to the unexpected modeling en＇ors than that of the SOS-RARE from the resolution point of view.
