The 8-node iso-parametric thin shell element was employed in the study of stress concentrations in the welded tubular “K” joint. Element equilibrium equations were derived using isoparametric formulation based on th...The 8-node iso-parametric thin shell element was employed in the study of stress concentrations in the welded tubular “K” joint. Element equilibrium equations were derived using isoparametric formulation based on thin shell theory. After assembly, the resulting system equations were solved using existing fortran programs. Numerical experiments were conducted to isolate and locate ideal gap (positions) for the two braces of the “K” joint. The nominal stresses were calculated from which stress concentration factors were obtained. The resulting stress concentration factors were presented both as tables and as figures. A good agreement between our solutions and those for model joints in the literature is good and acceptable. It was found that the wider apart the brace spacing is, the weaker the strength of the joint. It was also found that the best location for the braces occurs when the stress level changes sign either from positive to negative or vice versa at a critical sampling point.展开更多
BACKGROUND: The main aim of rehabilitation is to ameliorate motor function and use the damaged limbs in the activities of daily living. Several factors are needed in the self-recovery of the patients, and the most imp...BACKGROUND: The main aim of rehabilitation is to ameliorate motor function and use the damaged limbs in the activities of daily living. Several factors are needed in the self-recovery of the patients, and the most important one is to reduce spasm. Some mechanical repetitive movements can affect and change the excitability of motor neurons. OBJECTIVE: To observe the effect of repetitive training on ameliorating spasm of upper limbs of hemiplegic patients. DESIGN: A self-controlled observation before and after training. SETTING: Department of Rehabilitation, Xuanwu Hospital of Capital Medical University. PARTICIPANTS: Seven hemiplegic patients induced by brain injury were selected from the Department of Rehabilitation, Xuanwu Hospital, Capital Medical University from March to June in 2005. Inclusive criteria: ① Agreed and able to participate in the 30-minute training of hand function; ② Without disturbance of understanding. The patients with aphasia or apraxia, manifestation of shoulder pain, and severe neurological or mental defects. For the 7 patients, the Rivermead motor assessment (RMA) scores ranged 0-10 points, the Rivermead mobility index (RMI) ranged 1-3, and modified Ashworth scale (MAS) was grade 2-4. Their horizontal extension of shoulder joint was 0°-30°, anteflextion was 0°-50°, internal rotation was 50°-90°, external rotation was 0°-10°; and the elbow joint could extend for 15°-135°. METHODS: The viva 2 serial MOTOmed exerciser (Reck Company, Germany) was used. There were three phases of A-B-A. ① The phase A lasted for 1 week. The patient sat on a chair facting to the MOTOmed screen, and did the circumduction of upper limbs forwardly, 30 minutes a day and 5 days a week. ② The phase B lasted for 3 weeks. The training consisted of forward circumduction of upper limbs for 15 minutes, followed by backward ones for 15 minutes and 5-minute rest. ③ The training in the phase A was performed again for 2 weeks. The extensions of upper limbs were recorded at phase A, the extension and flexion of elbow joints were recorded at phase B, and the extensions were recorded at the second A phase. All the patients were evaluated by the same therapeutist. ① RMA was used to evaluate the motor function completely, including the motor control of both upper and lower limbs, but only the data of upper limbs were recommended to be used. The flexibility and concordance of upper limbs were described by detecting the ability of hand to move objects with 15 items, 2 grades for each item: 0 for could not complete and 1 for could complete. ② RMI was used to measure the flexion and extension of elbow joint and shoulder joint, the scores ranged from 0 (no movement and no obvious muscle contraction) to 5 (close to normal movement). ③ MAS was used to evaluate the muscle tension in clinic. Grade 1 for without abnormal increase of muscle tension, and grade 5 for muscle rigidity, and it was unable for passive movement. ④ Ranges of motion of elbow joint and should joint were measured using protractor. MAIN OUTCOME MEASURES: ① The strength of each limb to persist for 40 s recorded by two hand pedals; ② Changes of muscle tensions detected by the two hand pedals; ③ Changes of muscle contraction at the flexion and extension of ipsilateral limb recorded by EMG; ④ Minimal moment of iplateral end foot; ⑤ RMA; ⑥ RMI; ⑦ MAS; ⑧ Ranges of motion of elbow joints and shoulder joints. RESULTS: The functions were evaluated at 6 weeks after training. ① The strength of each limb to persist for 40 s was recorded, and the strength of the ipsilateral limb changed obviously from 20%-40% to 50%-70%. ② The muscle tensions detected by the two hand pedals changed from 2.2-4.0 N·m to 0.2-1.0 N·m. ③ EMG displayed that along with the enhancement of fast movements, the strength curve increased (the EMG for the extension of elbow joints were obvious). ④ The minimal moment of iplateral end foot was 5.0 N·m. ⑤ The RMA scores ranged 15-30 points. ⑥ The RMI ranged 4-5. ⑦ MAS were grades 0-2. ⑧ For shoulder joints, the ranges of motion were 90°-180° for external extension, 90° for anteflexion, 90° for internal rotation and 50°-75° for external rotation; For elbow joints, the extension of active movements was close to 0°. CONCLUSION: After repetitive movements, the strength of upper limb increased, the range of motion enlarged, and spasm reduced.展开更多
Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack...Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack pattern, failure mode and shear strength of joints are affected by the length of limb, and that shear strength and ductility increase with the length of limb; the joints with the flexural failure of the beam have better seismic behavior than those with the shear failure of the joint core.展开更多
The stability and ductility of four buckling-restrained braces (BRBs) with brace joints were studied. The load-carrying element of BRB was fabricated with steel (Chinese Q235), and a layer of colloidal silica sheet (0...The stability and ductility of four buckling-restrained braces (BRBs) with brace joints were studied. The load-carrying element of BRB was fabricated with steel (Chinese Q235), and a layer of colloidal silica sheet (0.5 mm in thickness) or four layers of plastic film (0.2 mm in thickness) were used as unbonding materials to provide space to prevent the buckling of inner core in higher modes and facilitate its lateral expansion in case of compression. Based on the equation of BRBs with brace joints of different restrained stiffnesses, the buckling load is calculated considering the initial geometric imperfections and residual stress, and the theoretical values agree well with the experiment results. It is concluded that the buckling load and ductility of BRBs are influenced greatly by the restrained stiffness of brace joints. If the restrained stiffness is deficient, the unstrained segment of BRBs with less stiffness will buckle firstly. As a result, the ultimate load of BRBs decreases, and the maximum compression load is reduced to about 65% of the maximum tension load; the stiffness also degenerates, and there is a long decreasing stage on the back-bone curve in compression phase; the ductility decreases, i.e., the ultimate tension ductility and ultimate compression ductility are approximately 15 and 1.3 respectively, and the cumulative plastic ductility is only approximately 200. If the restrained stiffness of joint is large enough, the stability will be improved as follows: the yielding strength and ultimate strength of BRBs are nearly the same, and there is an obvious strain intensification in both tension and compression phases; the ductility of brace also increases obviously, i.e., the ultimate tension ductility and ultimate compression ductility are both approximately 14, and the cumulative plastic ductility reaches 782.展开更多
背景:目前用于全膝关节置换的机器人系统设计的基本原理是将三维手术规划、术中危险区预警、实时数据反馈及机械臂辅助截骨等技术相结合,以实现全膝关节置换的精准化、个性化,这也恰好是它最大优势所在,因此近年来成为关节外科领域热点...背景:目前用于全膝关节置换的机器人系统设计的基本原理是将三维手术规划、术中危险区预警、实时数据反馈及机械臂辅助截骨等技术相结合,以实现全膝关节置换的精准化、个性化,这也恰好是它最大优势所在,因此近年来成为关节外科领域热点话题,备受关注。目的:文章将从机器人辅助全膝关节置换在关节外科领域的发展现状及其与传统全膝关节置换优劣势对比进行概述,此外,还将对机器人辅助全膝关节置换技术未来的发展进行展望。方法:应用计算机检索PubMed、中国知网、万方和维普数据库的相关文章,英文检索词:“robot OR robotic OR robotics OR robotically OR computer,total knee arthroplasty OR total knee replacement,TKA OR TKR”,中文检索词:“机器人辅助,计算机导航,全膝关节置换术”,最终纳入64篇文献进行综述分析。结果与结论:①用于辅助全膝关节置换的机器人系统根据其自由度分为主动式、半主动式和被动式。半主动式系统是目前使用最为广泛的机器人系统,该系统有效提高了全膝关节置换手术的精准性和个性化程度,但其高昂的使用成本与较长的学习曲线仍是在该领域内推广时需要权衡的主要因素。②机器人辅助全膝关节置换可实现膝关节局部三维空间的精准截骨、正确安置假体,已被广泛证明可以提供更好的假体植入精准度,减少影像学异常值,在术中可获得良好的软组织平衡,最终改善术后膝关节运动及功能状态。③但目前的机器人辅助系统依然存在客观的不足之处,包括不同机器人设备与术者之间的学习曲线问题、额外增加的安装和维护成本以及与机器人手术相关的潜在并发症,所以其能否让医疗系统及患者真正受益仍需要更长期的研究予以证明,机器人辅助系统也仍需进行更多实质性的改进。④机器人辅助全膝关节置换技术在临床上仍然处于初步研究阶段,并没有大范围地应用到临床,更加明确该技术的用法、完善该技术的临床操作规范和安全性成为了未来对该技术的研究侧重点。展开更多
文摘The 8-node iso-parametric thin shell element was employed in the study of stress concentrations in the welded tubular “K” joint. Element equilibrium equations were derived using isoparametric formulation based on thin shell theory. After assembly, the resulting system equations were solved using existing fortran programs. Numerical experiments were conducted to isolate and locate ideal gap (positions) for the two braces of the “K” joint. The nominal stresses were calculated from which stress concentration factors were obtained. The resulting stress concentration factors were presented both as tables and as figures. A good agreement between our solutions and those for model joints in the literature is good and acceptable. It was found that the wider apart the brace spacing is, the weaker the strength of the joint. It was also found that the best location for the braces occurs when the stress level changes sign either from positive to negative or vice versa at a critical sampling point.
文摘BACKGROUND: The main aim of rehabilitation is to ameliorate motor function and use the damaged limbs in the activities of daily living. Several factors are needed in the self-recovery of the patients, and the most important one is to reduce spasm. Some mechanical repetitive movements can affect and change the excitability of motor neurons. OBJECTIVE: To observe the effect of repetitive training on ameliorating spasm of upper limbs of hemiplegic patients. DESIGN: A self-controlled observation before and after training. SETTING: Department of Rehabilitation, Xuanwu Hospital of Capital Medical University. PARTICIPANTS: Seven hemiplegic patients induced by brain injury were selected from the Department of Rehabilitation, Xuanwu Hospital, Capital Medical University from March to June in 2005. Inclusive criteria: ① Agreed and able to participate in the 30-minute training of hand function; ② Without disturbance of understanding. The patients with aphasia or apraxia, manifestation of shoulder pain, and severe neurological or mental defects. For the 7 patients, the Rivermead motor assessment (RMA) scores ranged 0-10 points, the Rivermead mobility index (RMI) ranged 1-3, and modified Ashworth scale (MAS) was grade 2-4. Their horizontal extension of shoulder joint was 0°-30°, anteflextion was 0°-50°, internal rotation was 50°-90°, external rotation was 0°-10°; and the elbow joint could extend for 15°-135°. METHODS: The viva 2 serial MOTOmed exerciser (Reck Company, Germany) was used. There were three phases of A-B-A. ① The phase A lasted for 1 week. The patient sat on a chair facting to the MOTOmed screen, and did the circumduction of upper limbs forwardly, 30 minutes a day and 5 days a week. ② The phase B lasted for 3 weeks. The training consisted of forward circumduction of upper limbs for 15 minutes, followed by backward ones for 15 minutes and 5-minute rest. ③ The training in the phase A was performed again for 2 weeks. The extensions of upper limbs were recorded at phase A, the extension and flexion of elbow joints were recorded at phase B, and the extensions were recorded at the second A phase. All the patients were evaluated by the same therapeutist. ① RMA was used to evaluate the motor function completely, including the motor control of both upper and lower limbs, but only the data of upper limbs were recommended to be used. The flexibility and concordance of upper limbs were described by detecting the ability of hand to move objects with 15 items, 2 grades for each item: 0 for could not complete and 1 for could complete. ② RMI was used to measure the flexion and extension of elbow joint and shoulder joint, the scores ranged from 0 (no movement and no obvious muscle contraction) to 5 (close to normal movement). ③ MAS was used to evaluate the muscle tension in clinic. Grade 1 for without abnormal increase of muscle tension, and grade 5 for muscle rigidity, and it was unable for passive movement. ④ Ranges of motion of elbow joint and should joint were measured using protractor. MAIN OUTCOME MEASURES: ① The strength of each limb to persist for 40 s recorded by two hand pedals; ② Changes of muscle tensions detected by the two hand pedals; ③ Changes of muscle contraction at the flexion and extension of ipsilateral limb recorded by EMG; ④ Minimal moment of iplateral end foot; ⑤ RMA; ⑥ RMI; ⑦ MAS; ⑧ Ranges of motion of elbow joints and shoulder joints. RESULTS: The functions were evaluated at 6 weeks after training. ① The strength of each limb to persist for 40 s was recorded, and the strength of the ipsilateral limb changed obviously from 20%-40% to 50%-70%. ② The muscle tensions detected by the two hand pedals changed from 2.2-4.0 N·m to 0.2-1.0 N·m. ③ EMG displayed that along with the enhancement of fast movements, the strength curve increased (the EMG for the extension of elbow joints were obvious). ④ The minimal moment of iplateral end foot was 5.0 N·m. ⑤ The RMA scores ranged 15-30 points. ⑥ The RMI ranged 4-5. ⑦ MAS were grades 0-2. ⑧ For shoulder joints, the ranges of motion were 90°-180° for external extension, 90° for anteflexion, 90° for internal rotation and 50°-75° for external rotation; For elbow joints, the extension of active movements was close to 0°. CONCLUSION: After repetitive movements, the strength of upper limb increased, the range of motion enlarged, and spasm reduced.
文摘Four exterior joints with special-shaped columns which have different lengths of limbs are tested under low cyclic loading. Speeial-shaped columns adopted are L- and T-shaped in section. It can be concluded that crack pattern, failure mode and shear strength of joints are affected by the length of limb, and that shear strength and ductility increase with the length of limb; the joints with the flexural failure of the beam have better seismic behavior than those with the shear failure of the joint core.
基金Supported by the "Eleventh Five-Year Plan" for Science and Technology Research of China (No. 2006BAJ01B02-02-03)Natural Science Foundation of Heilongjiang Province (No. ZJG0701)+1 种基金National Natural Science Foundation of China (No. 90715021, No. 50678057, No. 50978080)Natural Scientific Research Innovation Foundation of Harbin Institute of Technology (No. HIT. NSRIF. 2009)
文摘The stability and ductility of four buckling-restrained braces (BRBs) with brace joints were studied. The load-carrying element of BRB was fabricated with steel (Chinese Q235), and a layer of colloidal silica sheet (0.5 mm in thickness) or four layers of plastic film (0.2 mm in thickness) were used as unbonding materials to provide space to prevent the buckling of inner core in higher modes and facilitate its lateral expansion in case of compression. Based on the equation of BRBs with brace joints of different restrained stiffnesses, the buckling load is calculated considering the initial geometric imperfections and residual stress, and the theoretical values agree well with the experiment results. It is concluded that the buckling load and ductility of BRBs are influenced greatly by the restrained stiffness of brace joints. If the restrained stiffness is deficient, the unstrained segment of BRBs with less stiffness will buckle firstly. As a result, the ultimate load of BRBs decreases, and the maximum compression load is reduced to about 65% of the maximum tension load; the stiffness also degenerates, and there is a long decreasing stage on the back-bone curve in compression phase; the ductility decreases, i.e., the ultimate tension ductility and ultimate compression ductility are approximately 15 and 1.3 respectively, and the cumulative plastic ductility is only approximately 200. If the restrained stiffness of joint is large enough, the stability will be improved as follows: the yielding strength and ultimate strength of BRBs are nearly the same, and there is an obvious strain intensification in both tension and compression phases; the ductility of brace also increases obviously, i.e., the ultimate tension ductility and ultimate compression ductility are both approximately 14, and the cumulative plastic ductility reaches 782.
文摘背景:目前用于全膝关节置换的机器人系统设计的基本原理是将三维手术规划、术中危险区预警、实时数据反馈及机械臂辅助截骨等技术相结合,以实现全膝关节置换的精准化、个性化,这也恰好是它最大优势所在,因此近年来成为关节外科领域热点话题,备受关注。目的:文章将从机器人辅助全膝关节置换在关节外科领域的发展现状及其与传统全膝关节置换优劣势对比进行概述,此外,还将对机器人辅助全膝关节置换技术未来的发展进行展望。方法:应用计算机检索PubMed、中国知网、万方和维普数据库的相关文章,英文检索词:“robot OR robotic OR robotics OR robotically OR computer,total knee arthroplasty OR total knee replacement,TKA OR TKR”,中文检索词:“机器人辅助,计算机导航,全膝关节置换术”,最终纳入64篇文献进行综述分析。结果与结论:①用于辅助全膝关节置换的机器人系统根据其自由度分为主动式、半主动式和被动式。半主动式系统是目前使用最为广泛的机器人系统,该系统有效提高了全膝关节置换手术的精准性和个性化程度,但其高昂的使用成本与较长的学习曲线仍是在该领域内推广时需要权衡的主要因素。②机器人辅助全膝关节置换可实现膝关节局部三维空间的精准截骨、正确安置假体,已被广泛证明可以提供更好的假体植入精准度,减少影像学异常值,在术中可获得良好的软组织平衡,最终改善术后膝关节运动及功能状态。③但目前的机器人辅助系统依然存在客观的不足之处,包括不同机器人设备与术者之间的学习曲线问题、额外增加的安装和维护成本以及与机器人手术相关的潜在并发症,所以其能否让医疗系统及患者真正受益仍需要更长期的研究予以证明,机器人辅助系统也仍需进行更多实质性的改进。④机器人辅助全膝关节置换技术在临床上仍然处于初步研究阶段,并没有大范围地应用到临床,更加明确该技术的用法、完善该技术的临床操作规范和安全性成为了未来对该技术的研究侧重点。
