A large variety of foreign bodies are swallowed by children, but the majority of those pass through the gastrointestinal tract without any adverse effects. The highest incidence of swallowed foreign bodies occurs in c...A large variety of foreign bodies are swallowed by children, but the majority of those pass through the gastrointestinal tract without any adverse effects. The highest incidence of swallowed foreign bodies occurs in children between 6 months and 3 years. We reported to you an unusually large foreign body ingested by a 2-year-old male patient who underwent a rigid oesophagoscopy but the foreign body had to be removed by open surgical technique. It is advisable to have a multidisciplinary approach while dealing with such cases.展开更多
A new ball screw dynamic model was developed under the adequate consideration of the interaction in the screw-nut assembly (not only the mutual-coupling factors but also the self-coupling factors) . Based on this mode...A new ball screw dynamic model was developed under the adequate consideration of the interaction in the screw-nut assembly (not only the mutual-coupling factors but also the self-coupling factors) . Based on this model,the multi-flexible body (MFB)dynamic model of ball screw feed drive system was then founded in order to take full account of the influencing factor of system flexibility and study the dynamic behaviors of the whole mechanical transmissions. Moreover,the MFB based state space modeling was proposed by modal state space method, which extraced the eigenmodes of more dominant modes and applied them into an MFB state space model,and realized the integrated model of servo drives and MFB mechanical transmissions more effectively and efficiently. In conclusion,the comparisons between simulations and experimental results show: the stiffness formulation of the ball screw assembly derived above is a suitable method for achieving accurate MFB models of ball screw mechanical transmission systems,this proposed MFB model is valid,and the integrated model of ball screw feed drive system is accurate and reliable. All these provide the important approaches and guidelines for dynamic characteristic study and selection of control parameters in the machine tool design period.展开更多
Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT ima...Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT images were obtained from a 38-year-old female volunteer.Following models were established and analyzed by Mimics14.0,Geomagic Studio 2013,ANSYS 14.0 software:the intact cervical model(C3-C7),corpectomy of C5 model,the model of conventional anterior screw plate system fixation(AP),and the model of anterior transpedicular screw artificial vertebral body sys-展开更多
文摘A large variety of foreign bodies are swallowed by children, but the majority of those pass through the gastrointestinal tract without any adverse effects. The highest incidence of swallowed foreign bodies occurs in children between 6 months and 3 years. We reported to you an unusually large foreign body ingested by a 2-year-old male patient who underwent a rigid oesophagoscopy but the foreign body had to be removed by open surgical technique. It is advisable to have a multidisciplinary approach while dealing with such cases.
基金National Science and Technology Major Project of China(No.2011ZX04016-02)
文摘A new ball screw dynamic model was developed under the adequate consideration of the interaction in the screw-nut assembly (not only the mutual-coupling factors but also the self-coupling factors) . Based on this model,the multi-flexible body (MFB)dynamic model of ball screw feed drive system was then founded in order to take full account of the influencing factor of system flexibility and study the dynamic behaviors of the whole mechanical transmissions. Moreover,the MFB based state space modeling was proposed by modal state space method, which extraced the eigenmodes of more dominant modes and applied them into an MFB state space model,and realized the integrated model of servo drives and MFB mechanical transmissions more effectively and efficiently. In conclusion,the comparisons between simulations and experimental results show: the stiffness formulation of the ball screw assembly derived above is a suitable method for achieving accurate MFB models of ball screw mechanical transmission systems,this proposed MFB model is valid,and the integrated model of ball screw feed drive system is accurate and reliable. All these provide the important approaches and guidelines for dynamic characteristic study and selection of control parameters in the machine tool design period.
基金supported by Natural Science Foundation of China(31170903)
文摘Objective Biomechanical properties of the anterior cervical pedicle screw artificial vertebral system and conventional anterior screw plate system were analyzed in lower cervical spine by finite element.Methods CT images were obtained from a 38-year-old female volunteer.Following models were established and analyzed by Mimics14.0,Geomagic Studio 2013,ANSYS 14.0 software:the intact cervical model(C3-C7),corpectomy of C5 model,the model of conventional anterior screw plate system fixation(AP),and the model of anterior transpedicular screw artificial vertebral body sys-
