Theoretical analysis and wind tunnel tests were carried out to study wind-induced intemal pressure response for the structure with single windward opening and background leakage. Its goveming differential equation was...Theoretical analysis and wind tunnel tests were carried out to study wind-induced intemal pressure response for the structure with single windward opening and background leakage. Its goveming differential equation was derived by the Bemoulli equation in an unsteady-isentropic form. Numerical examples were provided to study the additive damping caused by background leakage in laminar and turbulent flow, and the influence of background leakage on fluctuating internal pressure response was quantized. A series of models for low-rise building with various opening ratios and background leakage were designed and wind tunnel tests were conducted. It is shown that the fluctuating intemal pressure reduces when the background leakage are considered and that the effect of background leakage can be predicted accurately by the governing differential equation deduced in this paper.展开更多
To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the suffic...To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the sufficient bearing capacity and corrosion resistance of the structure,which can ensure the actual service life and safety of the tunnel,remain to be further improved.Glass Fiber Reinforced Plastics(GFRP)pipe,with light weight,high strength and corrosion resistance,has the potential to be applied to the deep tunnel structure.This paper proposed a new composite structure of deep tunnel lined with GFRP pipe,which consisted of three layers of concrete segment,cement paste and GFRP pipe.A new pipe-soil spring element model was proposed for the pipesoil interaction with gaps.Based on the C3D8R solid model and the Combin39 spring model,the finite element numerical analysis of the internal pressure status and external pressure stability of the structure was carried out.Combined with the checking calculation of the theoretical formula,the reliability of the two finite element models was confirmed.A set of numerical analysis methods for the design and optimization of the three-layer structure was established.The results showed that from the internal GFRP pipe to the outer concrete pipe,the pressure decreased from 0.5 to 0.32 MPa,due to the internal pressure was mainly undertaken by the inner GFRP pipe.The allowable buckling pressure of GFRP pipe under the cover of 5 GPa high modulus cement paste was 2.66 MPa.The application of GFRP pipe not only improves the overall performance of the deep tunnel structure but also improves the construction quality and safety.The three-layer structure built in this work is safe and economical.展开更多
Base on industrial research and experience, the process of methanol distillation is analyzed,and above all, a new concept of high pressure flowsheet and low pressure flowsheet is defined. The new configuration helps t...Base on industrial research and experience, the process of methanol distillation is analyzed,and above all, a new concept of high pressure flowsheet and low pressure flowsheet is defined. The new configuration helps to handle problems encountered in many factories in China. The inter influence between process and column internal pattern is also pointed out. Recommendation of new column internal designs is given. Finally, industrial examples tell the how the new concept works and the possibility of combining process to give more opens to solve engineering problems.展开更多
After reading the above mentioned article of [1], we identified a mistake considering the results of the paragraph “3.6. Nonlinear Parameters AP” and the related Table 5 (both on p. 512). Unfortunately, published Ta...After reading the above mentioned article of [1], we identified a mistake considering the results of the paragraph “3.6. Nonlinear Parameters AP” and the related Table 5 (both on p. 512). Unfortunately, published Table 5 is a duplicate of Table 4, and therefore it is not possible for the reader to comprehend any underlying interrelations. To correct this mistake, we would like to offer the corrected table (Table 5) as follows.展开更多
Thin spherical pressure hulls are used as a human occupancy in deep water applications.DNV and other standards specify the imperfection allowed for pressure hulls.Numerical analyses are carried out to find the bucklin...Thin spherical pressure hulls are used as a human occupancy in deep water applications.DNV and other standards specify the imperfection allowed for pressure hulls.Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls,considering the geometric and material non-linearities.It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls.Moreover,if the manufacturing imperfections are considered in the inelastic numerical analysis,still there is a reduction in the buckling pressure.Design criteria,for deep water pressure hulls,is that both buckling pressure and yield pressure must be greater than the design pressure.In the elastic analysis,if t/D>0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis,the buckling pressure is falling below the yield pressure for all t/D ratios.Hence,inelastic numerical analysis with manufacturing imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.展开更多
基金Project (No. 50578144) supported by the National Natural ScienceFoundation of China
文摘Theoretical analysis and wind tunnel tests were carried out to study wind-induced intemal pressure response for the structure with single windward opening and background leakage. Its goveming differential equation was derived by the Bemoulli equation in an unsteady-isentropic form. Numerical examples were provided to study the additive damping caused by background leakage in laminar and turbulent flow, and the influence of background leakage on fluctuating internal pressure response was quantized. A series of models for low-rise building with various opening ratios and background leakage were designed and wind tunnel tests were conducted. It is shown that the fluctuating intemal pressure reduces when the background leakage are considered and that the effect of background leakage can be predicted accurately by the governing differential equation deduced in this paper.
基金This project was supported by the Fundamental Research Funds for the Central Universities(WUT:2018IB001)the Fundamental Research Funds for the Central Universities(WUT:2019III130CG).
文摘To date,with the increasing attention of countries to urban drainage system,more and more regions around the world have begun to build water conveyance tunnels,sewage pressure deep tunnels and so on.However,the sufficient bearing capacity and corrosion resistance of the structure,which can ensure the actual service life and safety of the tunnel,remain to be further improved.Glass Fiber Reinforced Plastics(GFRP)pipe,with light weight,high strength and corrosion resistance,has the potential to be applied to the deep tunnel structure.This paper proposed a new composite structure of deep tunnel lined with GFRP pipe,which consisted of three layers of concrete segment,cement paste and GFRP pipe.A new pipe-soil spring element model was proposed for the pipesoil interaction with gaps.Based on the C3D8R solid model and the Combin39 spring model,the finite element numerical analysis of the internal pressure status and external pressure stability of the structure was carried out.Combined with the checking calculation of the theoretical formula,the reliability of the two finite element models was confirmed.A set of numerical analysis methods for the design and optimization of the three-layer structure was established.The results showed that from the internal GFRP pipe to the outer concrete pipe,the pressure decreased from 0.5 to 0.32 MPa,due to the internal pressure was mainly undertaken by the inner GFRP pipe.The allowable buckling pressure of GFRP pipe under the cover of 5 GPa high modulus cement paste was 2.66 MPa.The application of GFRP pipe not only improves the overall performance of the deep tunnel structure but also improves the construction quality and safety.The three-layer structure built in this work is safe and economical.
文摘Base on industrial research and experience, the process of methanol distillation is analyzed,and above all, a new concept of high pressure flowsheet and low pressure flowsheet is defined. The new configuration helps to handle problems encountered in many factories in China. The inter influence between process and column internal pattern is also pointed out. Recommendation of new column internal designs is given. Finally, industrial examples tell the how the new concept works and the possibility of combining process to give more opens to solve engineering problems.
文摘After reading the above mentioned article of [1], we identified a mistake considering the results of the paragraph “3.6. Nonlinear Parameters AP” and the related Table 5 (both on p. 512). Unfortunately, published Table 5 is a duplicate of Table 4, and therefore it is not possible for the reader to comprehend any underlying interrelations. To correct this mistake, we would like to offer the corrected table (Table 5) as follows.
基金The authors gratefully acknowledge the support extended by the Ministry of Earth Science,Government of India,in funding this researchThe authors would like to express sin-cere thanks to the Director of National Institute of Ocean Technology for his continued support of research activities.
文摘Thin spherical pressure hulls are used as a human occupancy in deep water applications.DNV and other standards specify the imperfection allowed for pressure hulls.Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls,considering the geometric and material non-linearities.It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls.Moreover,if the manufacturing imperfections are considered in the inelastic numerical analysis,still there is a reduction in the buckling pressure.Design criteria,for deep water pressure hulls,is that both buckling pressure and yield pressure must be greater than the design pressure.In the elastic analysis,if t/D>0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis,the buckling pressure is falling below the yield pressure for all t/D ratios.Hence,inelastic numerical analysis with manufacturing imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.
