Purpose:Under-foot impact loadings can cause serious lower limb injuries in many activities,such asautomobile collisions and underbody explosions to military vehicles.The present study aims to comparethe biomechanical...Purpose:Under-foot impact loadings can cause serious lower limb injuries in many activities,such asautomobile collisions and underbody explosions to military vehicles.The present study aims to comparethe biomechanical responses of the mainstream vehicle occupant dummies with the human body lowerlimb model and analyze their robustness and applicability for assessing lower limb injury risk in underfoot impact loading environments.Methods:The Hybrid III model,the test device for human occupant restraint(THOR)model,and a hybridhuman body model with the human active lower limb model were adopted for under-foot impactanalysis regarding different impact velocities and initial lower limb postures.Results:The results show that the 2 dummy models have larger peak tibial axial force and highersensitivity to the impact velocities and initial postures than the human lower limb model.In particular,the Hybrid III dummy model presented extremely larger peak tibial axial forces than the human lowerlimb model.In the case of minimal difference in tibial axial force,Hybrid III's tibial axial force(7.5 KN)isstill 312.5%that of human active lower limb's(2.4 KN).Even with closer peak tibial axial force values,thebiomechanical response curve shapes of the THOR model show significant differences from the humanlower limb model.Conclusion:Based on the present results,the Hybrid III dummy cannot be used to evaluate the lowerlimb injury risk in under-foot loading environments.In contrast,potential improvement in ankle biofidelity and related soft tissues of the THOR dummy can be implemented in the future for betterapplicability.展开更多
Context/objectives: The COVID-19 pandemic has disrupted all programs, potentially impacting access to health services for children under 5 years old. The Far North of Cameroon is one of the northern regions with a pre...Context/objectives: The COVID-19 pandemic has disrupted all programs, potentially impacting access to health services for children under 5 years old. The Far North of Cameroon is one of the northern regions with a prevalence of malnourished children ranging from 5% to 10%. Due to the barrier measures implemented to combat the pandemic, many parents are reluctant to take their children to healthcare facilities. Some of these children were benefiting from the Ambulatory Care Center (ACC) program prior to the COVID-19 outbreak. The main objective of this research is to assess the impact of COVID-19 on access to health services for children under 5 in the Mayo Tsanaga (MT) and Logone & Chari (LC) departments. The implementation of barrier measures could significantly increase the risk of malnutrition among children under 5 years old. Method: A cross-sectional analytical study was conducted in the MT and LC departments, employing both retrospective and prospective approaches. Data was collected through questionnaire, interview guide and a review of existing data prior to the pandemic (DHIS 2). Kobo Collect software was used for data collection, and R software was used for analysis. Results: Children who benefitted from the ACC program during the COVID-19 period were found to have a lower prevalence of malnutrition compared to those who did not benefit (OR: 0.09, CI {0.0 - 0.44}). Conclusion: COVID-19 has led to a decrease in the utilization of health facilities in both departments of the study, resulting in an increase in health issues such as malnutrition among children under 5 years old. Various policies have been implemented to improve attendance at health facilities.展开更多
This article discusses the dynamic computation of the closed cylindrical shell under impact load. In the text we analyse the changes of the momenta and the energy on each stage in the impact process, take into account...This article discusses the dynamic computation of the closed cylindrical shell under impact load. In the text we analyse the changes of the momenta and the energy on each stage in the impact process, take into account the effect of the mass of impact object and the system of the closed cylindrical shell by impact, and transform the distributed mass of the whole cylindrical shell into an only concentrated 'equivalent mass' by the method of reduced mass. Consequently we derive the dynamic factor of the closed cylindrical shell due to impact load.The method proposed in this paper is of practical worth and is more convenient in calculations.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant No.51875187,32171305)Hunan YouthTalent Program(Grant No.2020RC3016)+1 种基金Natural Science Foundation of Chongqing(Grant No.cstc2021jcyj-msxmX0109)Chongqing Technology Innovation and Application DevelopmentProject(CSTB2023YSZX-JSX0003).
文摘Purpose:Under-foot impact loadings can cause serious lower limb injuries in many activities,such asautomobile collisions and underbody explosions to military vehicles.The present study aims to comparethe biomechanical responses of the mainstream vehicle occupant dummies with the human body lowerlimb model and analyze their robustness and applicability for assessing lower limb injury risk in underfoot impact loading environments.Methods:The Hybrid III model,the test device for human occupant restraint(THOR)model,and a hybridhuman body model with the human active lower limb model were adopted for under-foot impactanalysis regarding different impact velocities and initial lower limb postures.Results:The results show that the 2 dummy models have larger peak tibial axial force and highersensitivity to the impact velocities and initial postures than the human lower limb model.In particular,the Hybrid III dummy model presented extremely larger peak tibial axial forces than the human lowerlimb model.In the case of minimal difference in tibial axial force,Hybrid III's tibial axial force(7.5 KN)isstill 312.5%that of human active lower limb's(2.4 KN).Even with closer peak tibial axial force values,thebiomechanical response curve shapes of the THOR model show significant differences from the humanlower limb model.Conclusion:Based on the present results,the Hybrid III dummy cannot be used to evaluate the lowerlimb injury risk in under-foot loading environments.In contrast,potential improvement in ankle biofidelity and related soft tissues of the THOR dummy can be implemented in the future for betterapplicability.
文摘Context/objectives: The COVID-19 pandemic has disrupted all programs, potentially impacting access to health services for children under 5 years old. The Far North of Cameroon is one of the northern regions with a prevalence of malnourished children ranging from 5% to 10%. Due to the barrier measures implemented to combat the pandemic, many parents are reluctant to take their children to healthcare facilities. Some of these children were benefiting from the Ambulatory Care Center (ACC) program prior to the COVID-19 outbreak. The main objective of this research is to assess the impact of COVID-19 on access to health services for children under 5 in the Mayo Tsanaga (MT) and Logone & Chari (LC) departments. The implementation of barrier measures could significantly increase the risk of malnutrition among children under 5 years old. Method: A cross-sectional analytical study was conducted in the MT and LC departments, employing both retrospective and prospective approaches. Data was collected through questionnaire, interview guide and a review of existing data prior to the pandemic (DHIS 2). Kobo Collect software was used for data collection, and R software was used for analysis. Results: Children who benefitted from the ACC program during the COVID-19 period were found to have a lower prevalence of malnutrition compared to those who did not benefit (OR: 0.09, CI {0.0 - 0.44}). Conclusion: COVID-19 has led to a decrease in the utilization of health facilities in both departments of the study, resulting in an increase in health issues such as malnutrition among children under 5 years old. Various policies have been implemented to improve attendance at health facilities.
文摘This article discusses the dynamic computation of the closed cylindrical shell under impact load. In the text we analyse the changes of the momenta and the energy on each stage in the impact process, take into account the effect of the mass of impact object and the system of the closed cylindrical shell by impact, and transform the distributed mass of the whole cylindrical shell into an only concentrated 'equivalent mass' by the method of reduced mass. Consequently we derive the dynamic factor of the closed cylindrical shell due to impact load.The method proposed in this paper is of practical worth and is more convenient in calculations.
