As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the...As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.展开更多
Background:Bone stress injuries(BSIs)are common in female runners,and recurrent BSI rates are high.Previous work suggests an association between higher impact loading during running and tibial BSI.However,it is unknow...Background:Bone stress injuries(BSIs)are common in female runners,and recurrent BSI rates are high.Previous work suggests an association between higher impact loading during running and tibial BSI.However,it is unknown whether impact loading and fatigue-related loading changes discriminate women with a history of multiple BSIs.This study compared impact variables at the beginning of a treadmill run to exertion andthe changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of single or multiple BSIs.Methods:We enrolled 45 female runners(aged 18-40 years)for this cross-sectional study:having no history of diagnosed lower extremity BSI(N-BSI,n=14);a history of 1 lower extremity BSI(1-BSI,n=16);and diagnosed by imaging,or a history of multiple(>3)lower extremity BSIs(M-BSI,n=15).Participants completed a 5-km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit.The vertical average loading rate(VALR),vertical instantaneous loading rate(VILR),vertical stiffness during impact via instrumented treadmill,and tibial shock determined as the peak po sitive tibial acceleration via Inertial Measurement Unit were measured at the beginning and the end of the run.Results:There were no differences between groups in VALR,VILR,vertical stiffness,or tibial shock in a fresh or exerted condition.However,compared to N-BSI,women with M-BSI had greater increase with exertion in VALR(-1.8%vs.6.1%,p=0.01)and VILR(1.5%vs.4.8%,p=0.03).Similarly,compared to N-BSI,vertical stiffness increased more with exertion among women with M-BSI(-0.9%vs.7.3%,p=0.006)and 1-BSI(-0.9%vs.1.8%,p=0.05).Finally,compared to N-BSI,the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI(0.9%vs.5.5%,p=0.03)and 1-BSI(0.9%vs.11.2%,p=0.02).Conclusion:Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI.These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.展开更多
基金supported in part by National Natural Science Foundation of China(62203127)Basic and Applied Basic Research Project of Guangzhou City(2023A04J1712)+1 种基金The Foshan-HKUST Projects Program(FSUST19-FYTRI01)GDAS’Project of Science and Technology Development(2020GDASYL-20200202001).
文摘As a key component of injection molding,multi-cavity hot runner(MCHR)system faces the crucial problem of polymer melt filling imbalance among the cavities.The thermal imbalance in the system has been considered as the leading cause.Hence,the solution may rest with the synchronization of those heating processes in MCHR system.This paper proposes a’Master-Slave’generalized predictive synchronization control(MS-GPSC)method with’Mr.Slowest’strategy for preheating stage of MCHR system.The core of the proposed method is choosing the heating process with slowest dynamics as the’Master’to track the setpoint,while the other heating processes are treated as‘Slaves’tracking the output of’Master’.This proposed method is shown to have the good ability of temperature synchronization.The corresponding analysis is conducted on parameters tuning and stability,simulations and experiments show the strategy is effective.
基金supported in part by appointments to the Department of Defense Research Participation Program at the U.S.Army Research Institute of Environmental Medicine administered by the Oak Ridge Institute for Science and Educationsupport from the U.S.Department of Defense+2 种基金Defense Health ProgramJoint Program Committee(W81XWH-16-1-0652)the National Institutes of Health shared instrumentation grant(S10 RR023405)。
文摘Background:Bone stress injuries(BSIs)are common in female runners,and recurrent BSI rates are high.Previous work suggests an association between higher impact loading during running and tibial BSI.However,it is unknown whether impact loading and fatigue-related loading changes discriminate women with a history of multiple BSIs.This study compared impact variables at the beginning of a treadmill run to exertion andthe changes in those variables with exertion among female runners with no history of BSI as well as among those with a history of single or multiple BSIs.Methods:We enrolled 45 female runners(aged 18-40 years)for this cross-sectional study:having no history of diagnosed lower extremity BSI(N-BSI,n=14);a history of 1 lower extremity BSI(1-BSI,n=16);and diagnosed by imaging,or a history of multiple(>3)lower extremity BSIs(M-BSI,n=15).Participants completed a 5-km race speed run on an instrumented treadmill while wearing an Inertial Measurement Unit.The vertical average loading rate(VALR),vertical instantaneous loading rate(VILR),vertical stiffness during impact via instrumented treadmill,and tibial shock determined as the peak po sitive tibial acceleration via Inertial Measurement Unit were measured at the beginning and the end of the run.Results:There were no differences between groups in VALR,VILR,vertical stiffness,or tibial shock in a fresh or exerted condition.However,compared to N-BSI,women with M-BSI had greater increase with exertion in VALR(-1.8%vs.6.1%,p=0.01)and VILR(1.5%vs.4.8%,p=0.03).Similarly,compared to N-BSI,vertical stiffness increased more with exertion among women with M-BSI(-0.9%vs.7.3%,p=0.006)and 1-BSI(-0.9%vs.1.8%,p=0.05).Finally,compared to N-BSI,the increase in tibial shock from fresh to exerted condition was greater among women with M-BSI(0.9%vs.5.5%,p=0.03)and 1-BSI(0.9%vs.11.2%,p=0.02).Conclusion:Women with 1-BSI or M-BSIs experience greater exertion-related increases in impact loading than women with N-BSI.These observations imply that exertion-related changes in gait biomechanics may contribute to risk of BSI.