Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineerin...Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.展开更多
BACKGROUND Brain arteriovenous malformations(bAVMs)remains one of the most prevalent causes of intracranial hemorrhage and stroke-like syndromes in the young adult population.Although it has been agreed upon that defi...BACKGROUND Brain arteriovenous malformations(bAVMs)remains one of the most prevalent causes of intracranial hemorrhage and stroke-like syndromes in the young adult population.Although it has been agreed upon that definitive treatment using either single or multi-modal approach is warranted for successful bAVM management,much debate still revolves regarding the optimal timing of definitive treatment.CASE SUMMARY In this report,we present a case of delayed,definitive endovascular treatment for ruptured bAVM in a 21-year-old female,3 mo post-ictus.The bAVM,with a left pericallosal feeding artery and cortical draining veins,was successfully obliterated through embolization using the Onyx 18.On follow-up the patient has recommenced her daily activities and experiences only mild occasional headaches with mild motor deficits.The report leads to our review on an important issue regarding the optimal timing of ruptured bAVM definitive management and bring forward the current evidence available on delayed vs immediate definitive bAVM intervention.We also highlight current issues that need to be addressed for clearer guidelines on definitive therapy initiation.CONCLUSION Current treatment paradigms of ruptured bAVM remains elusive,with substantial heterogeneity in the current literature.A consensus on the definition of“acute”vs“delayed”,management goal,follow-up length and outcome parameters are required to support formation of a clear paradigm.展开更多
基金financially supported by the National Key Research and Development Program of China-Young Scientist Project(No.2024YFC2815400)the National Natural Science Foundation of China(No.52588202).
文摘Deep-sea mining has emerged as a critical solution to address global resource shortages;however,the mechanical interaction between tracked mining vehicles(TMVs)and soft seabed sediments presents fundamental engineering challenges.This study establishes a multiscale modelling framework coupling the discrete element method(DEM)with multi-body dynamics(MBD)to investigate track-seabed dynamic interactions across three operational modes:flat terrain,slope climbing,and ditch surmounting.The simulation framework,validated against laboratory experiments,systematically evaluates the influence of grouser geometry(involute,triangular,and pin-type)and traveling speed(0.2–1.0 m/s)on traction performance,slip rate,and ground pressure distribution.Results reveal rate-dependent traction mechanisms governed by soil microstructural responses:higher speeds enhance peak traction but exacerbate slip instability on complex terrain.Critical operational thresholds are established—0.7 m/s for flat terrain,≤0.5 m/s for slopes and ditches—with distinct grouser optimization strategies:involute grousers achieve 35%–40%slip reduction on slopes through progressive soil engagement,while triangular grousers provide optimal impact resistance during ditch crossing with 30%–35%performance improvement.These findings provide quantitative design criteria and operational guidelines for optimizing TMV structural parameters and control strategies,offering a robust theoretical foundation for enhancing the performance,safety,and reliability of deep-sea mining equipment in complex submarine environments.
文摘BACKGROUND Brain arteriovenous malformations(bAVMs)remains one of the most prevalent causes of intracranial hemorrhage and stroke-like syndromes in the young adult population.Although it has been agreed upon that definitive treatment using either single or multi-modal approach is warranted for successful bAVM management,much debate still revolves regarding the optimal timing of definitive treatment.CASE SUMMARY In this report,we present a case of delayed,definitive endovascular treatment for ruptured bAVM in a 21-year-old female,3 mo post-ictus.The bAVM,with a left pericallosal feeding artery and cortical draining veins,was successfully obliterated through embolization using the Onyx 18.On follow-up the patient has recommenced her daily activities and experiences only mild occasional headaches with mild motor deficits.The report leads to our review on an important issue regarding the optimal timing of ruptured bAVM definitive management and bring forward the current evidence available on delayed vs immediate definitive bAVM intervention.We also highlight current issues that need to be addressed for clearer guidelines on definitive therapy initiation.CONCLUSION Current treatment paradigms of ruptured bAVM remains elusive,with substantial heterogeneity in the current literature.A consensus on the definition of“acute”vs“delayed”,management goal,follow-up length and outcome parameters are required to support formation of a clear paradigm.
