The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response charact...The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves, and accordingly to offer valuable findings for engineering, the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different embedment depths in response to two wave spectra.The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain. By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder, experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory, and detailed comparisons were also carried out between the single and continuous cylinders. Some new findings and the corresponding analysis are reported in present paper. The investigation on continuous cylinders will be used in particular for reference in engineering applications because information is scarce on studying such kind of problem both analytically and experimentally.展开更多
In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological con...In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological conditions such as high ground stress, folded structure tilted roof asymmetry and soft wall rock, and built the tilt layered roof structural mechanics model to clarify the increase span mechanism of the weak coal instability. Then, we proposed the combined control system including roof inclined truss cable, coal-side cable-channel steel and intensive bolt support. And then by building the structural mechanics model of roof inclined truss cable system, the support principle was described. Besides, according to this model, we deduced the calculation formula of cable anchoring force and its tensile stress. Finally surrounding rock control technology of large section roadway in fold coal pillar area was formed. Field practice shows that the greatest roof convergence of gangue replacement roadway is 158 mm and coal-side deformation is 243 mm. Roadway deformation is controlled effectively and technical support is provided for replacement mining.展开更多
A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous...A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous (ARMAX) input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this papel; the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input and outputs, respectively. The experimental data, used in this study, were collected from a full-scale rough vertical cylinder at the Delft Hydraulics Laboratory. The practicality of the proposed method and also its efficiency in structural modeling were demonstrated through applying two hydrodynamic force components. For this purpose, an ARMAX model is first used to capture the dynamics of the process, relating in-line forces provided by water waves; secondly, the TARMAX model was applied to modeling and analysis of the lift forces on the cylinder. The evaluation of the lift force by the TARMAX model shows the model is successful in modeling the force from the surface elevation.展开更多
Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. ...Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. Following the layerwise theory, a variable kinematic model that incorporates mechanics and thermal conditions is also presented. The new element has a field of displacement compatible with the cylindrical shell element or plate and it can be used as a rigid element for this structural element.ln the laminate model construction, adjacent layers are arranged as bonded layers. The layer has a unique constant thickness that can be different to each layer. The fiber reinforced is used and the fibers in a laminate may be oriented arbitrarily. The shear stress is adopted equal to zero because the thin thickness, on the other hand, the normal stress is maintained in order to ensure the compatibility of stress in material. The previously authors of this methods neglect the implications of thermal effects on cylindrical shells structures. Thermal effects become important when the structure has to operate in either extremely hot or cold temperature environments. These extreme conditions may severely affect the response of structure in two distinct ways: (1) induction of thermal stresses due to differences in the coefficients of thermal expansion between the various composite plies and layers and (2) temperature dependence of the elastic properties. Only a limited amount of work has been reported concerning this topic. All in all, the main contribution of this work is the consideration of this kinematic for cylindrical shells that incorporate mechanics and thermal conditions. In addition, numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of cylindrical shells with these characteristics.展开更多
Different solvothermal reactions of ZnC2O_(4)with oxalic acid(H_(2)ox)and 1,2,4-triazole(Htrz)successfully gave a new quaternary(NJTU-Bai83,NJTU-Bai=Nanjing Tech University Bai's group)and a new quinary(NJTU-Bai84...Different solvothermal reactions of ZnC2O_(4)with oxalic acid(H_(2)ox)and 1,2,4-triazole(Htrz)successfully gave a new quaternary(NJTU-Bai83,NJTU-Bai=Nanjing Tech University Bai's group)and a new quinary(NJTU-Bai84)anionic metal-organic frameworks(MOFs),where NJTU-Bai83=(Me_(2)NH_(2))2[Zn_(3)(trz)_(2)(ox)_(3)]·2H_(2)O and NJTU-Bai84=(Me_(2)NH_(2))[Zn_(3)(trz)_(3)(ox)_(2)]·H_(2)O,respectively.With the[Zn_(2)(ox)4(trz)_(2)]secondary building unit(SBU)in NJTU-Bai83 replaced by the[Zn_(3)(ox)_(2)(trz)_(6)]and planar[Zn(ox)_(2)(trz)_(2)]ones in NJTU-Bai84,2D supramolecular building layers(SBLs)are changed from the A-layer and B-layer to another A-layer,while pillars are transformed from the tetrahedral[Zn(ox)_(2)(trz)_(2)]SBU to the irregular tetrahedral[Zn(ox)_(2)(trz)_(2)]and planar[Zn(ox)_(2)(trz)_(2)]SBUs.Thus,cdq-topological quaternary NJTU-Bai83 is tuned to(4,4,8)-c new topological quinary NJTU-Bai84.Two MOFs were well characterized by powder X-ray diffraction,thermogravimetric analysis,elemental analysis,etc.CCDC:2351819,NJTU-Bai83;2351820,NJTU-Bai84.展开更多
文摘The response of dynamic wave pressures on structures would be more complicated and bring about new phenomena under the dynamic interaction between soil and structure. In order to better understand the response characteristics on deeply embedded large cylindrical structures under random waves, and accordingly to offer valuable findings for engineering, the authors designed wave flume experiments to investigate comparatively dynamic wave pressures on a single and on continuous cylinders with two different embedment depths in response to two wave spectra.The time histories of the water surface elevation and the corresponding dynamic wave pressures exerted on the cylinder were analyzed in the frequency domain. By calculating the transfer function and spectral density for dynamic wave pressures along the height and around the circumference of the cylinder, experimental results of the single cylinder were compared with the theoretical results based on the linear diffraction theory, and detailed comparisons were also carried out between the single and continuous cylinders. Some new findings and the corresponding analysis are reported in present paper. The investigation on continuous cylinders will be used in particular for reference in engineering applications because information is scarce on studying such kind of problem both analytically and experimentally.
文摘In order to solve the surrounding rock control problem of large section gangue replacement roadway under complicated conditions, this paper analyzed the impact to the roadway controlling produced by the geological conditions such as high ground stress, folded structure tilted roof asymmetry and soft wall rock, and built the tilt layered roof structural mechanics model to clarify the increase span mechanism of the weak coal instability. Then, we proposed the combined control system including roof inclined truss cable, coal-side cable-channel steel and intensive bolt support. And then by building the structural mechanics model of roof inclined truss cable system, the support principle was described. Besides, according to this model, we deduced the calculation formula of cable anchoring force and its tensile stress. Finally surrounding rock control technology of large section roadway in fold coal pillar area was formed. Field practice shows that the greatest roof convergence of gangue replacement roadway is 158 mm and coal-side deformation is 243 mm. Roadway deformation is controlled effectively and technical support is provided for replacement mining.
文摘A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous (ARMAX) input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this papel; the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input and outputs, respectively. The experimental data, used in this study, were collected from a full-scale rough vertical cylinder at the Delft Hydraulics Laboratory. The practicality of the proposed method and also its efficiency in structural modeling were demonstrated through applying two hydrodynamic force components. For this purpose, an ARMAX model is first used to capture the dynamics of the process, relating in-line forces provided by water waves; secondly, the TARMAX model was applied to modeling and analysis of the lift forces on the cylinder. The evaluation of the lift force by the TARMAX model shows the model is successful in modeling the force from the surface elevation.
文摘Thermal effects are incorporated into developed discrete layer mechanics for two-dimensional cylindrical shells structures. Finite element equations are developed according to layerwise theory of laminated structure. Following the layerwise theory, a variable kinematic model that incorporates mechanics and thermal conditions is also presented. The new element has a field of displacement compatible with the cylindrical shell element or plate and it can be used as a rigid element for this structural element.ln the laminate model construction, adjacent layers are arranged as bonded layers. The layer has a unique constant thickness that can be different to each layer. The fiber reinforced is used and the fibers in a laminate may be oriented arbitrarily. The shear stress is adopted equal to zero because the thin thickness, on the other hand, the normal stress is maintained in order to ensure the compatibility of stress in material. The previously authors of this methods neglect the implications of thermal effects on cylindrical shells structures. Thermal effects become important when the structure has to operate in either extremely hot or cold temperature environments. These extreme conditions may severely affect the response of structure in two distinct ways: (1) induction of thermal stresses due to differences in the coefficients of thermal expansion between the various composite plies and layers and (2) temperature dependence of the elastic properties. Only a limited amount of work has been reported concerning this topic. All in all, the main contribution of this work is the consideration of this kinematic for cylindrical shells that incorporate mechanics and thermal conditions. In addition, numerical results are presented to demonstrate the capability of the current formulation to represent the behavior of cylindrical shells with these characteristics.
文摘Different solvothermal reactions of ZnC2O_(4)with oxalic acid(H_(2)ox)and 1,2,4-triazole(Htrz)successfully gave a new quaternary(NJTU-Bai83,NJTU-Bai=Nanjing Tech University Bai's group)and a new quinary(NJTU-Bai84)anionic metal-organic frameworks(MOFs),where NJTU-Bai83=(Me_(2)NH_(2))2[Zn_(3)(trz)_(2)(ox)_(3)]·2H_(2)O and NJTU-Bai84=(Me_(2)NH_(2))[Zn_(3)(trz)_(3)(ox)_(2)]·H_(2)O,respectively.With the[Zn_(2)(ox)4(trz)_(2)]secondary building unit(SBU)in NJTU-Bai83 replaced by the[Zn_(3)(ox)_(2)(trz)_(6)]and planar[Zn(ox)_(2)(trz)_(2)]ones in NJTU-Bai84,2D supramolecular building layers(SBLs)are changed from the A-layer and B-layer to another A-layer,while pillars are transformed from the tetrahedral[Zn(ox)_(2)(trz)_(2)]SBU to the irregular tetrahedral[Zn(ox)_(2)(trz)_(2)]and planar[Zn(ox)_(2)(trz)_(2)]SBUs.Thus,cdq-topological quaternary NJTU-Bai83 is tuned to(4,4,8)-c new topological quinary NJTU-Bai84.Two MOFs were well characterized by powder X-ray diffraction,thermogravimetric analysis,elemental analysis,etc.CCDC:2351819,NJTU-Bai83;2351820,NJTU-Bai84.