Rotational failure analysis of spherical-cylindrical shell pressure controllers related to gas hydrate drilling investigations

In situ pressure-preserved coring(IPP-Coring)technology is considered one of the most efficient methods for assessing resources.However,seal failure caused by the rotation of pressure controllers greatly affects the success of pressure coring.In this paper,a novel spherical-cylindrical shell pressure controller was proposed.The finite element analysis model was used to analyze the stress distribution and deformation characteristics of the pressure controller at different rotation angles.The seal failure mechanism caused by the rotation of the pressure controller was discussed.The stress deviation rate was defined to quantitatively characterize the stress concentration.Based on the test equipment designed in this laboratory,the ultimate bearing strength of the pressure controller was tested.The results show that the rotation of the valve cover causes an increase in the deformation on its lower side.Furthermore,the specific sealing pressure in the weak zone is greatly reduced by a statistically significant amount,resulting in seal failure.When the valve cover rotates 5°around the major axis,the stress deviation rate is-92.6%.To prevent rotating failure of the pressure controller,it is necessary to control the rotation angle of the valve cover within 1°around the major axis.The results of this research can help engineers reduce failure-related accidents,provide countermeasures for pressure coring,and contribute to the exploration and evaluation of deep oil and gas resources.

Testing the consistency of propagation between light and heavy cosmic ray nuclei

One of the fundamental challenges in cosmic ray physics is to explain the nature of cosmic ray acceleration and propagation mechanisms.Owing to the precise cosmic ray data measured by recent space experiments,we can investigate cosmic ray acceleration and propagation models more comprehensively and reliably.In this paper,we combine the secondary-to-primary ratios and primary spectra measured by PAMELA,AMS02,ACE-CRIS,and Voyager-1 to constrain the cosmic ray source and transport parameters.The study shows that the Z>2 data yield a medium-energy diffusion slope δ_(2)~(0.42,0.48)and a high-energy slope δ_(3)~(0.22,0.34).The Z≤2 species place a looser constraint on δ_(2)~(0.38,0.47)but a tighter constraint onδ3~(0.21,0.30).The overlaps imply that heavy and light particles can provide compatible results at medium to high energies.Moreover,both the light and heavy nuclei indicate a consistent diffusion slope variation ΔδH at 200~300 GV.At low energies,significant disagreements exist between heavy and light elements.The boron-to-carbon ratio requires a much larger diffusion slope shift ΔδL at approximately 4 GV or a stronger Alfvén velocity vA than the low-mass data.This indicates that the heavy and light particles may suffer different low-energy transport behaviors in the galaxy.However,a better understanding of the consistency/inconsistency between the heavy and light cosmic rays relies on more precise cross-sections,better constraints on correlations in systematic errors of data,a more accurate estimation of the galaxy halo size,and a more robust description of solar modulation during the reversal period of the heliospheric magnetic field.