The dynamics of satellites formation is of great interest for the space mission. This work discusses a more efficient model of the relative motion dynamics of satellites formation. The model is based on employing the ...The dynamics of satellites formation is of great interest for the space mission. This work discusses a more efficient model of the relative motion dynamics of satellites formation. The model is based on employing the concepts restricted three-body problem (R3BP) and for more accuracy, it considers the effects of both oblateness and radiation pressure on deputy relative motion w.r.t the chief satellite. A model of deputy relative motion w.r.t the chief satellite is derived in the local-vertical local-horizontal system and simplified assuming the concept of the circular restricted three-body problem (CR3BP). The deputy equations of motion were rewritten in the form of recurrence relations and solved numerically using the Lie series approach. Assuming that the formation is revolving around the Moon in the Earth-Moon system, the effects of both oblateness and radiation pressure on the deputy satellite orbit were assessed through a particular example of satellites formation. A comparison between the perturbed and unperturbed R3BP shows a significant difference in the deputy relative position that has to be considered for the formation dynamics.展开更多
The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Gene...The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Generalized Jacobian Matrix of a multi arm FFSR is proposed to enable the coordinated motion of all the other arms while one arm is tracing a given path so that there is no disturbance on the body, and the problem of attitude disturbance with an operating multi arm FFSR is thereby better resolved. The simulation run with a dual arm FFSR system verifies the effectiveness of this algorithm.展开更多
Purpose: Belt electrode skeletal muscle electrical stimulation (B-SES) can stimulate large portions of muscles including deep sites without localisation of the stimulation area. The purpose of this study is to investi...Purpose: Belt electrode skeletal muscle electrical stimulation (B-SES) can stimulate large portions of muscles including deep sites without localisation of the stimulation area. The purpose of this study is to investigate both immediate treatment effects of B-SES and long-term treatment effects of B-SES with passive exercise on range of motion (ROM) and muscle tone of lower extremities in bedridden elderly patients. Methods: Outcome measures before and after B-SES treatment alone (4 Hz, 20 min, both lower extremities) were examined for the immediate effect. Outcome measures were: ROM and Modified Ashworth scale (MAS) of hip flexion and adduction;knee flexion and extension;and knee joint distance at position of flexion abduction in hip (distance of knee). A randomized crossover trial was conducted to examine the long-term effect of adding B-SES to passive exercise on ROM and MAS. Results and Discussion: The immediate effect study had 18 patients. ROM and MAS of 4 joint angles in 2 joints and distance of knee significantly improved after B-SES treatment. The long-term effect study had 11 patients. Friedman test revealed ROM and MAS of 4 joint angles in 2 joints and distance of knee significantly improved during B-SES intervention but not control intervention. B-SES in addition to passive stretch has a more statistically significant effect on contracture and spasticity in large portions of the lower extremities of bedridden elderly patients than passive stretching alone. Conclusions: We consider B-SES a useful tool to improve the ROM in lower extremities of bedridden patients.展开更多
Mitral regurgitation (MR) is a highly prevalent valvular heart disease globally,with untreated severe cases demonstrating associations with elevated morbidity,mortality,and adverse cardiovascular outcomes.[1,2]While t...Mitral regurgitation (MR) is a highly prevalent valvular heart disease globally,with untreated severe cases demonstrating associations with elevated morbidity,mortality,and adverse cardiovascular outcomes.[1,2]While transcatheter edge-toedge repair (TEER) has emerged as an alternative option for high surgical risk patients with severe MR,[3,4]severe MR of Carpentier class IIIa (characterized by restricted leaflet motion during both systole and diastole) has been considered a relative contraindication for TEER interventions due to stenosis risk and procedural complexity.[5,6]展开更多
文摘The dynamics of satellites formation is of great interest for the space mission. This work discusses a more efficient model of the relative motion dynamics of satellites formation. The model is based on employing the concepts restricted three-body problem (R3BP) and for more accuracy, it considers the effects of both oblateness and radiation pressure on deputy relative motion w.r.t the chief satellite. A model of deputy relative motion w.r.t the chief satellite is derived in the local-vertical local-horizontal system and simplified assuming the concept of the circular restricted three-body problem (CR3BP). The deputy equations of motion were rewritten in the form of recurrence relations and solved numerically using the Lie series approach. Assuming that the formation is revolving around the Moon in the Earth-Moon system, the effects of both oblateness and radiation pressure on the deputy satellite orbit were assessed through a particular example of satellites formation. A comparison between the perturbed and unperturbed R3BP shows a significant difference in the deputy relative position that has to be considered for the formation dynamics.
文摘The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Generalized Jacobian Matrix of a multi arm FFSR is proposed to enable the coordinated motion of all the other arms while one arm is tracing a given path so that there is no disturbance on the body, and the problem of attitude disturbance with an operating multi arm FFSR is thereby better resolved. The simulation run with a dual arm FFSR system verifies the effectiveness of this algorithm.
文摘Purpose: Belt electrode skeletal muscle electrical stimulation (B-SES) can stimulate large portions of muscles including deep sites without localisation of the stimulation area. The purpose of this study is to investigate both immediate treatment effects of B-SES and long-term treatment effects of B-SES with passive exercise on range of motion (ROM) and muscle tone of lower extremities in bedridden elderly patients. Methods: Outcome measures before and after B-SES treatment alone (4 Hz, 20 min, both lower extremities) were examined for the immediate effect. Outcome measures were: ROM and Modified Ashworth scale (MAS) of hip flexion and adduction;knee flexion and extension;and knee joint distance at position of flexion abduction in hip (distance of knee). A randomized crossover trial was conducted to examine the long-term effect of adding B-SES to passive exercise on ROM and MAS. Results and Discussion: The immediate effect study had 18 patients. ROM and MAS of 4 joint angles in 2 joints and distance of knee significantly improved after B-SES treatment. The long-term effect study had 11 patients. Friedman test revealed ROM and MAS of 4 joint angles in 2 joints and distance of knee significantly improved during B-SES intervention but not control intervention. B-SES in addition to passive stretch has a more statistically significant effect on contracture and spasticity in large portions of the lower extremities of bedridden elderly patients than passive stretching alone. Conclusions: We consider B-SES a useful tool to improve the ROM in lower extremities of bedridden patients.
基金supported by the 1·3·5 Project for Disciplines of Excellence from West China Hospital of Sichuan University(ZYGD23021&23HXFH009)Sichuan Science and Technology Program(No.2025ZNSFSC1698)the Sichuan Provincial Cadre Health Research Program(ZH2024-103).
文摘Mitral regurgitation (MR) is a highly prevalent valvular heart disease globally,with untreated severe cases demonstrating associations with elevated morbidity,mortality,and adverse cardiovascular outcomes.[1,2]While transcatheter edge-toedge repair (TEER) has emerged as an alternative option for high surgical risk patients with severe MR,[3,4]severe MR of Carpentier class IIIa (characterized by restricted leaflet motion during both systole and diastole) has been considered a relative contraindication for TEER interventions due to stenosis risk and procedural complexity.[5,6]
基金国家高技术研究发展计划(863)(the National High-Tech Research and Development Plan of China under Grant No.2006AA01Z324)西北工业大学研究生创业种子基金(the Graduate Starting Seed Fund of Northwestern Polytechnical UniversityNo.Z200752)。
