Clearances in joints of a mechanical multibody system can induce impulsive forces, leading to vibrations that compromise the system’s reliability, stability, and lifespan. Through dynamic analysis, designers can inve...Clearances in joints of a mechanical multibody system can induce impulsive forces, leading to vibrations that compromise the system’s reliability, stability, and lifespan. Through dynamic analysis, designers can investigate the effects of the clearances on the dynamics of the multibody system. A revolute joint with clearance exhibits three motions which are;free-flight, impact and continuous contact motion modes. Therefore, a multibody system with n-number of revolute clearance joints will exhibit 3n motion modes which are a combination of the three motions in each joint. This study investigates experimentally the nine motion modes in a mechanical system with two revolute clearance joints. A slider crank mechanism has been used as the demonstrative example. We observed that the experimental curve exhibits a greater impact compared to the simulation curve. In conclusion, this experimental investigation offers valuable insights into the dynamics of planar mechanical systems with multiple clearance revolute joints. Utilizing a slider-crank mechanism for data acquisition, the study successfully confirmed seven out of nine motion modes previously identified in numerical research. The missing modes are attributed to inherent complexities in real-world systems, such as journal-bearing misalignment.展开更多
The objective of the present study was to investigate our novel methods for the repair of massive cartilage defects by joint distraction and motion using an external fixator. In this study, we used a rabbit model of m...The objective of the present study was to investigate our novel methods for the repair of massive cartilage defects by joint distraction and motion using an external fixator. In this study, we used a rabbit model of massive articular cartilage defect in order to evaluate the effectiveness of using joint distraction and motion with a ring-type external fixator. This external fixator has a hinged joint with a center of rotation along the femoral transepicondylar axis, which allows the knee joint to freely flex and extend. Mesenchymal cells from bone marrow, induced by spongialization, were differentiated into mature chondrocytes and formed hyaline-like cartilage as a result of joint distraction and movement. The transplantation of autologous cells expanded from bone-marrow-derived mesenchymal cells, concentrated autologous bone marrow aspirate, and concentrated autologous peripheral blood cells were all effective in promoting cartilage repair. The quality of the cartilage after long-term joint distraction for 6 months was inferior to that after 12 weeks. In general, weight bearing on the regenerated cartilage promoted cartilage repair, although this effect differed based on when gradual weight bearing was begun. Specifically, gradual weight bearing beginning at 9 weeks produced superior results to that beginning at 6 weeks. Our methods provide an optimal environment for cartilage regeneration.展开更多
This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. H...This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.展开更多
Background: The shape of the capitellum has been traditionally described in anatomy books as part of a sphere. Alteration in the capitellar morphology following pathologies such as fractures, osteochondrosis, and dege...Background: The shape of the capitellum has been traditionally described in anatomy books as part of a sphere. Alteration in the capitellar morphology following pathologies such as fractures, osteochondrosis, and degenerative arthritis has been associated with less optimum functional results. Aim: To define the relationship between the sphericity of the capitellar morphology as measured on trauma series plain radiographs and the elbow range of motion. Methods: 40 patients were included in the study. All patients recruited from the upper limb clinics presented with non-elbow joint-related complaints. The elbow range of motion was measured using a standardized technique. Digital anteroposterior and lateral radiographs of patients’ elbows were used to measure capitellar circularity using the ImageJ processing program and circularity calculation equation. Correlation analyses were conducted between the degree of capitellar sphericity and elbow range of motion. Results: The results of measurements from the anteroposterior radiographs showed a positive correlation between increased circularity and an increase in the range of flexion, pronation, and supination. The range of extension decreased with the increased circularity of the capitellum. This trend was repeated with measures of lateral radiographs but was statistically not significant. Conclusion: Native capitellar circularity has an impact on the elbow range of motion. This should be put into consideration when dealing with pathologies that affect capitellar morphology.展开更多
In the domain of autonomous industrial manipulators,precise positioning and appropriate posture selection in path planning are pivotal for tasks involving obstacle avoidance,such as handling,heat sealing,and stacking....In the domain of autonomous industrial manipulators,precise positioning and appropriate posture selection in path planning are pivotal for tasks involving obstacle avoidance,such as handling,heat sealing,and stacking.While Multi-Degree-of-Freedom(MDOF)manipulators offer kinematic redundancy,aiding in the derivation of optimal inverse kinematic solutions to meet position and posture requisites,their path planning entails intricate multiobjective optimization,encompassing path,posture,and joint motion optimization.Achieving satisfactory results in practical scenarios remains challenging.In response,this study introduces a novel Reverse Path Planning(RPP)methodology tailored for industrial manipulators.The approach commences by conceptualizing the manipulator’s end-effector as an agent within a reinforcement learning(RL)framework,wherein the state space,action set,and reward function are precisely defined to expedite the search for an initial collision-free path.To enhance convergence speed,the Q-learning algorithm in RL is augmented with Dyna-Q.Additionally,we formulate the cylindrical bounding box of the manipulator based on its Denavit-Hartenberg(DH)parameters and propose a swift collision detection technique.Furthermore,the motion performance of the end-effector is refined through a bidirectional search,and joint weighting coefficients are introduced to mitigate motion in high-power joints.The efficacy of the proposed RPP methodology is rigorously examined through extensive simulations conducted on a six-degree-of-freedom(6-DOF)manipulator encountering two distinct obstacle configurations and target positions.Experimental results substantiate that the RPP method adeptly orchestrates the computation of the shortest collision-free path while adhering to specific posture constraints at the target point.Moreover,itminimizes both posture angle deviations and joint motion,showcasing its prowess in enhancing the operational performance of MDOF industrial manipulators.展开更多
目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试...目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试验组行康玛士(Kindman)布冰袋冰水冷疗。比较2组患者术后疼痛程度[数字评分法(NPS)]、肿胀程度、关节活动度及并发症,并分析患者生活质量(SF-36量表)及对护理满意度。结果与对照组比较,试验组8、24、48 h NRS评分依次降低(P<0.05),且不同时间比较具有交互效应(P<0.05)。与对照组比较,试验组在8、24、48 h的肿胀程度降低效果更明显(P<0.05)。与对照组比较,试验组关节活动度优良率更高(P<0.05)。试验组并发症发生率低于对照组(P<0.05)。与对照组比较,试验组术后3、5 d SF-16评分均显著升高(P<0.05)。试验组护理满意度高于对照组(P<0.05)。结论康玛士布冰袋冰水冷疗在关节手术患者术后行关节锻炼中可明显降低患者疼痛程度,改善关节活动度,提高生活质量。展开更多
Corresponding to the sliding and the overturning failure,the elementary motion modes of caisson breakwater include the horizontal-rotational oscillation coupled motion,the horizontal sliding-rotational oscillation cou...Corresponding to the sliding and the overturning failure,the elementary motion modes of caisson breakwater include the horizontal-rotational oscillation coupled motion,the horizontal sliding-rotational oscillation coupled motion,the horizontal vibrating-uplift rocking coupled motion,and the horizontal sliding-uplift rocking coupled motion.The motion mode of a caisson will transform from one to another depending on the wave forces and the motion behaviors of the caisson.The numerical models of four motion modes of caisson are developed,and the numerical simulation procedure for joint motion process of various modes of caisson breakwater under wave excitation is presented and tested by a physical model experiment.It is concluded that the simulation procedure is reliable and can be applied to the dynamic stability analysis of caisson breakwaters.展开更多
目的探讨透析中关节活动度运动对维持性血液透析(maintenance hemodialysis,MHD)患者的影响。方法选取2023年4月─10月南昌大学第一附属医院血液透析中心的MHD患者为研究对象,由研究者随机投掷硬币将东湖院区和象湖院区随机分为试验组...目的探讨透析中关节活动度运动对维持性血液透析(maintenance hemodialysis,MHD)患者的影响。方法选取2023年4月─10月南昌大学第一附属医院血液透析中心的MHD患者为研究对象,由研究者随机投掷硬币将东湖院区和象湖院区随机分为试验组和对照组,对照组患者给予常规护理,试验组患者在常规护理的基础上实施透析中关节活动度运动。比较2组患者干预前后的疲乏量表-14(fatigue scale-14,FS-14)得分、6分钟步行试验(6 minutes walk test,6MWT)、30秒坐立试验(30-second sit-to-stand test,30s-STS)和简短生活质量量表得分(36-item short form health survey,SF-36)差异。结果透析中关节活动度运动干预后试验组患者的FS-14得分低于对照组(Z=-7.782,P<0.001),6MWT(t=5.812,P<0.001)、30s-STS(t=6.111,P<0.001)、SF-36得分(t=2.583,P=0.012)高于对照组。结论透析中关节活动度运动可有效缓解患者的疲乏症状,提高运动能力、生活质量。展开更多
文摘Clearances in joints of a mechanical multibody system can induce impulsive forces, leading to vibrations that compromise the system’s reliability, stability, and lifespan. Through dynamic analysis, designers can investigate the effects of the clearances on the dynamics of the multibody system. A revolute joint with clearance exhibits three motions which are;free-flight, impact and continuous contact motion modes. Therefore, a multibody system with n-number of revolute clearance joints will exhibit 3n motion modes which are a combination of the three motions in each joint. This study investigates experimentally the nine motion modes in a mechanical system with two revolute clearance joints. A slider crank mechanism has been used as the demonstrative example. We observed that the experimental curve exhibits a greater impact compared to the simulation curve. In conclusion, this experimental investigation offers valuable insights into the dynamics of planar mechanical systems with multiple clearance revolute joints. Utilizing a slider-crank mechanism for data acquisition, the study successfully confirmed seven out of nine motion modes previously identified in numerical research. The missing modes are attributed to inherent complexities in real-world systems, such as journal-bearing misalignment.
文摘The objective of the present study was to investigate our novel methods for the repair of massive cartilage defects by joint distraction and motion using an external fixator. In this study, we used a rabbit model of massive articular cartilage defect in order to evaluate the effectiveness of using joint distraction and motion with a ring-type external fixator. This external fixator has a hinged joint with a center of rotation along the femoral transepicondylar axis, which allows the knee joint to freely flex and extend. Mesenchymal cells from bone marrow, induced by spongialization, were differentiated into mature chondrocytes and formed hyaline-like cartilage as a result of joint distraction and movement. The transplantation of autologous cells expanded from bone-marrow-derived mesenchymal cells, concentrated autologous bone marrow aspirate, and concentrated autologous peripheral blood cells were all effective in promoting cartilage repair. The quality of the cartilage after long-term joint distraction for 6 months was inferior to that after 12 weeks. In general, weight bearing on the regenerated cartilage promoted cartilage repair, although this effect differed based on when gradual weight bearing was begun. Specifically, gradual weight bearing beginning at 9 weeks produced superior results to that beginning at 6 weeks. Our methods provide an optimal environment for cartilage regeneration.
基金supported by the National Natural Science Foundation of China (11072122)
文摘This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.
文摘Background: The shape of the capitellum has been traditionally described in anatomy books as part of a sphere. Alteration in the capitellar morphology following pathologies such as fractures, osteochondrosis, and degenerative arthritis has been associated with less optimum functional results. Aim: To define the relationship between the sphericity of the capitellar morphology as measured on trauma series plain radiographs and the elbow range of motion. Methods: 40 patients were included in the study. All patients recruited from the upper limb clinics presented with non-elbow joint-related complaints. The elbow range of motion was measured using a standardized technique. Digital anteroposterior and lateral radiographs of patients’ elbows were used to measure capitellar circularity using the ImageJ processing program and circularity calculation equation. Correlation analyses were conducted between the degree of capitellar sphericity and elbow range of motion. Results: The results of measurements from the anteroposterior radiographs showed a positive correlation between increased circularity and an increase in the range of flexion, pronation, and supination. The range of extension decreased with the increased circularity of the capitellum. This trend was repeated with measures of lateral radiographs but was statistically not significant. Conclusion: Native capitellar circularity has an impact on the elbow range of motion. This should be put into consideration when dealing with pathologies that affect capitellar morphology.
基金supported by the National Natural Science Foundation of China under Grant No.62001199Fujian Province Nature Science Foundation under Grant No.2023J01925.
文摘In the domain of autonomous industrial manipulators,precise positioning and appropriate posture selection in path planning are pivotal for tasks involving obstacle avoidance,such as handling,heat sealing,and stacking.While Multi-Degree-of-Freedom(MDOF)manipulators offer kinematic redundancy,aiding in the derivation of optimal inverse kinematic solutions to meet position and posture requisites,their path planning entails intricate multiobjective optimization,encompassing path,posture,and joint motion optimization.Achieving satisfactory results in practical scenarios remains challenging.In response,this study introduces a novel Reverse Path Planning(RPP)methodology tailored for industrial manipulators.The approach commences by conceptualizing the manipulator’s end-effector as an agent within a reinforcement learning(RL)framework,wherein the state space,action set,and reward function are precisely defined to expedite the search for an initial collision-free path.To enhance convergence speed,the Q-learning algorithm in RL is augmented with Dyna-Q.Additionally,we formulate the cylindrical bounding box of the manipulator based on its Denavit-Hartenberg(DH)parameters and propose a swift collision detection technique.Furthermore,the motion performance of the end-effector is refined through a bidirectional search,and joint weighting coefficients are introduced to mitigate motion in high-power joints.The efficacy of the proposed RPP methodology is rigorously examined through extensive simulations conducted on a six-degree-of-freedom(6-DOF)manipulator encountering two distinct obstacle configurations and target positions.Experimental results substantiate that the RPP method adeptly orchestrates the computation of the shortest collision-free path while adhering to specific posture constraints at the target point.Moreover,itminimizes both posture angle deviations and joint motion,showcasing its prowess in enhancing the operational performance of MDOF industrial manipulators.
文摘目的探究冰水冷疗在关节手术患者术后行关节锻炼镇痛中的有效性。方法选取钦州市第一人民医院行关节置换手术及关节镜手术的400例患者,随机数表法将其分为试验组和对照组,每组200例。2组进行关节锻炼后,对照组给予固体冰袋冷疗治疗;试验组行康玛士(Kindman)布冰袋冰水冷疗。比较2组患者术后疼痛程度[数字评分法(NPS)]、肿胀程度、关节活动度及并发症,并分析患者生活质量(SF-36量表)及对护理满意度。结果与对照组比较,试验组8、24、48 h NRS评分依次降低(P<0.05),且不同时间比较具有交互效应(P<0.05)。与对照组比较,试验组在8、24、48 h的肿胀程度降低效果更明显(P<0.05)。与对照组比较,试验组关节活动度优良率更高(P<0.05)。试验组并发症发生率低于对照组(P<0.05)。与对照组比较,试验组术后3、5 d SF-16评分均显著升高(P<0.05)。试验组护理满意度高于对照组(P<0.05)。结论康玛士布冰袋冰水冷疗在关节手术患者术后行关节锻炼中可明显降低患者疼痛程度,改善关节活动度,提高生活质量。
基金supported by the National Natural Science Foundation of China(Grant No.50979069)the Science and Technology Project of West China Traffic Construction(Grant No.200632800003-06)
文摘Corresponding to the sliding and the overturning failure,the elementary motion modes of caisson breakwater include the horizontal-rotational oscillation coupled motion,the horizontal sliding-rotational oscillation coupled motion,the horizontal vibrating-uplift rocking coupled motion,and the horizontal sliding-uplift rocking coupled motion.The motion mode of a caisson will transform from one to another depending on the wave forces and the motion behaviors of the caisson.The numerical models of four motion modes of caisson are developed,and the numerical simulation procedure for joint motion process of various modes of caisson breakwater under wave excitation is presented and tested by a physical model experiment.It is concluded that the simulation procedure is reliable and can be applied to the dynamic stability analysis of caisson breakwaters.
文摘目的探讨透析中关节活动度运动对维持性血液透析(maintenance hemodialysis,MHD)患者的影响。方法选取2023年4月─10月南昌大学第一附属医院血液透析中心的MHD患者为研究对象,由研究者随机投掷硬币将东湖院区和象湖院区随机分为试验组和对照组,对照组患者给予常规护理,试验组患者在常规护理的基础上实施透析中关节活动度运动。比较2组患者干预前后的疲乏量表-14(fatigue scale-14,FS-14)得分、6分钟步行试验(6 minutes walk test,6MWT)、30秒坐立试验(30-second sit-to-stand test,30s-STS)和简短生活质量量表得分(36-item short form health survey,SF-36)差异。结果透析中关节活动度运动干预后试验组患者的FS-14得分低于对照组(Z=-7.782,P<0.001),6MWT(t=5.812,P<0.001)、30s-STS(t=6.111,P<0.001)、SF-36得分(t=2.583,P=0.012)高于对照组。结论透析中关节活动度运动可有效缓解患者的疲乏症状,提高运动能力、生活质量。
