A new measurement and analysis method was proposed to investigate the changes in elbow joint moments that occur with the use of a front-wheeled walker. A strain gauge-based walker instrumentation system was developed ...A new measurement and analysis method was proposed to investigate the changes in elbow joint moments that occur with the use of a front-wheeled walker. A strain gauge-based walker instrumentation system was developed to monitor the hand loads during walker-assisted walking and integrated with an upper extremity biomechanical model. Preliminary system data were collected for 12 subjects following informed consent. Bilateral upper extremity kinematic data were acquired with a six-camera motion analysis system. Internal joint moments at the elbow were determined in the three clinical planes using the inverse dynamics method. Results showed that during a walker-assisted gait elbow joint moments mainly distributed in the walker stance period. There was a noted demand on the elbow extensor in the sagittal plane with the greatest record as 0.381 N·m/(kg·m). An interesting "bare phase" of mean elbow joint moments was also found in phase angle-240o-340o of gait cycle. Complete description of elbow joint moments of walker-assisted gait may provide insight into walker use parameters and rehabilitative strategies.展开更多
While walkers are commonly prescribed to improve patient stability and ambulatory ability,quantitative study of the biomechanical and functional requirements for effective walker use is limited.To investigate the chan...While walkers are commonly prescribed to improve patient stability and ambulatory ability,quantitative study of the biomechanical and functional requirements for effective walker use is limited.To investigate the changes in wrist joint moments that occur with the use of a standard walker,a strain gauge-based walker instrumentation sys- tem was developed for the measurement of wrist joint moments.This walker dynamometer was integrated with an up- per extremity biomechanical model.Preliminary system data were collected for twelve healthy,right-handed young a- dults following informed consent.Bilateral upper extremity kinematic data were acquired with a six-camera motion a- nalysis system.Internal joint moments at the wrist were determined in the three clinical planes using the inverse dy- namics method.Results showed that during a walker-assisted gait there were several typical demands of wrist abduc- tor,adductor,flexor and external rotator.An interesting'bare phase'of wrist joint moments was also found in phase angle[-30°,30°]of gait cycle.Complete description of wrist joint moments during walker-assisted gait may pro- vide insight into walker use parameters and rehabilitative strategies.展开更多
We investigated bending moment resistance under diagonal compression load of corner doweled joints with plywood members. Joint members were made of 11-ply hardwood plywood of 19 mm thickness. Dowels were fabricated of...We investigated bending moment resistance under diagonal compression load of corner doweled joints with plywood members. Joint members were made of 11-ply hardwood plywood of 19 mm thickness. Dowels were fabricated of Beech and Hornbeam species. Their diameters(6, 8 and 10 mm) and depths of penetration(9, 13 and 17 mm) in joint members were chosen variables in our experiment. By increasing the connector's diameter from 6 to 8 mm, the bending moment resistance under diagonal compressive load was increased, while it decreased when the diameter was increased from 8 to 10 mm. The bending moment resistance under diagonal compressive load was increased by increasing the dowel's depth of penetration. Joints made with dowels of Beech had higher resistance than dowels of Hornbeam. Highest resisting moment(45.18 N·m) was recorded for joints assembled with 8 mm Beech dowels penetrating 17 mm into joint members Lowest resisting moment(13.35 N·m) was recorded for joints assembled with 6 mm Hornbeam dowels and penetrating 9 mm into joint members.展开更多
In this paper explicit expressions and some recurrence relations are derived for marginal and joint moment generating functions of generalized order statistics from Erlang-truncated exponential distribution. The resul...In this paper explicit expressions and some recurrence relations are derived for marginal and joint moment generating functions of generalized order statistics from Erlang-truncated exponential distribution. The results for k-th record values and order statistics are deduced from the relations derived. Further, a characterizing result of this distribution on using the conditional expectation of function of generalized order statistics is discussed.展开更多
Recent advances In the theory of ∑ relationships lead to the Investigation of moments needed to derive the relavant joint probability densities. These together with the linear theory of relationships, make possible t...Recent advances In the theory of ∑ relationships lead to the Investigation of moments needed to derive the relavant joint probability densities. These together with the linear theory of relationships, make possible the calcualtion of therelationships from ∑1 to ∑2 one by one. The superior performance ofour new ∑4 and ∑r relationships, for example, with respect to the older ∑1 and ∑3 formulas strongly suggests a deeper study of the pertinent moments. In this paper a new concept, the cosine moment, is introduced which, together with a certain integral theorem, permits the derivation of the relevant joint probability densities. These lead in turn to the derivation of all ∑ relationships valid for all the space groups.展开更多
A joint combining riveting and bonding is considered in terms of structural performance if the composite structure has a mismatched stiffener. The transfer loading is correlated with high performance aerospace joints ...A joint combining riveting and bonding is considered in terms of structural performance if the composite structure has a mismatched stiffener. The transfer loading is correlated with high performance aerospace joints to increase delamination resistance in the out-of-plane direction. However, combined joints (rivet/bonded) will create a bearing area that induces another potential damage source aside from secondary bending moment on the edge of the stiffener. Another problem is that the structure is difficult to be inspected by using conventional methods because of limited accessibility. The use of embedded fiber Bragg grating (FBG) technology in the structure as a strain sensor can potentially solve the problem in structures that have a stiffness mismatch. The FBG can be used to detect and characterize delamination before it reaches a critical stage. The model used to represent this problem is a thin composite stiffened skin under two load cases: tension and three-point bending. Finite element modeling using a traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. Experiments were presented to determine the distribution of load in a combined joint under both loading cases using ideal loads to create a secondary bending moment and bearing loads in the stiffness-mismatched structure. In this research, the FBG successfully detected and characterized the delamination caused in both loading cases. In addition, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace the conventional mechanical graph in composite structural health monitoring in real applications.展开更多
基金National Natural Science Foundation of China (No. 60501005)National High Technology Research and Development Program of China(No. 2007AA04Z236)Key Program of Tianjin Science and Technology Support Plan (No. 07ZCKFSF01300)
文摘A new measurement and analysis method was proposed to investigate the changes in elbow joint moments that occur with the use of a front-wheeled walker. A strain gauge-based walker instrumentation system was developed to monitor the hand loads during walker-assisted walking and integrated with an upper extremity biomechanical model. Preliminary system data were collected for 12 subjects following informed consent. Bilateral upper extremity kinematic data were acquired with a six-camera motion analysis system. Internal joint moments at the elbow were determined in the three clinical planes using the inverse dynamics method. Results showed that during a walker-assisted gait elbow joint moments mainly distributed in the walker stance period. There was a noted demand on the elbow extensor in the sagittal plane with the greatest record as 0.381 N·m/(kg·m). An interesting "bare phase" of mean elbow joint moments was also found in phase angle-240o-340o of gait cycle. Complete description of elbow joint moments of walker-assisted gait may provide insight into walker use parameters and rehabilitative strategies.
基金Supported by National Natural Science Foundation of China(60501005)Key Program of Tianjin SciePnee Technology Support Plan(07ZCKFSF01300)
文摘While walkers are commonly prescribed to improve patient stability and ambulatory ability,quantitative study of the biomechanical and functional requirements for effective walker use is limited.To investigate the changes in wrist joint moments that occur with the use of a standard walker,a strain gauge-based walker instrumentation sys- tem was developed for the measurement of wrist joint moments.This walker dynamometer was integrated with an up- per extremity biomechanical model.Preliminary system data were collected for twelve healthy,right-handed young a- dults following informed consent.Bilateral upper extremity kinematic data were acquired with a six-camera motion a- nalysis system.Internal joint moments at the wrist were determined in the three clinical planes using the inverse dy- namics method.Results showed that during a walker-assisted gait there were several typical demands of wrist abduc- tor,adductor,flexor and external rotator.An interesting'bare phase'of wrist joint moments was also found in phase angle[-30°,30°]of gait cycle.Complete description of wrist joint moments during walker-assisted gait may pro- vide insight into walker use parameters and rehabilitative strategies.
文摘We investigated bending moment resistance under diagonal compression load of corner doweled joints with plywood members. Joint members were made of 11-ply hardwood plywood of 19 mm thickness. Dowels were fabricated of Beech and Hornbeam species. Their diameters(6, 8 and 10 mm) and depths of penetration(9, 13 and 17 mm) in joint members were chosen variables in our experiment. By increasing the connector's diameter from 6 to 8 mm, the bending moment resistance under diagonal compressive load was increased, while it decreased when the diameter was increased from 8 to 10 mm. The bending moment resistance under diagonal compressive load was increased by increasing the dowel's depth of penetration. Joints made with dowels of Beech had higher resistance than dowels of Hornbeam. Highest resisting moment(45.18 N·m) was recorded for joints assembled with 8 mm Beech dowels penetrating 17 mm into joint members Lowest resisting moment(13.35 N·m) was recorded for joints assembled with 6 mm Hornbeam dowels and penetrating 9 mm into joint members.
文摘In this paper explicit expressions and some recurrence relations are derived for marginal and joint moment generating functions of generalized order statistics from Erlang-truncated exponential distribution. The results for k-th record values and order statistics are deduced from the relations derived. Further, a characterizing result of this distribution on using the conditional expectation of function of generalized order statistics is discussed.
文摘Recent advances In the theory of ∑ relationships lead to the Investigation of moments needed to derive the relavant joint probability densities. These together with the linear theory of relationships, make possible the calcualtion of therelationships from ∑1 to ∑2 one by one. The superior performance ofour new ∑4 and ∑r relationships, for example, with respect to the older ∑1 and ∑3 formulas strongly suggests a deeper study of the pertinent moments. In this paper a new concept, the cosine moment, is introduced which, together with a certain integral theorem, permits the derivation of the relevant joint probability densities. These lead in turn to the derivation of all ∑ relationships valid for all the space groups.
文摘A joint combining riveting and bonding is considered in terms of structural performance if the composite structure has a mismatched stiffener. The transfer loading is correlated with high performance aerospace joints to increase delamination resistance in the out-of-plane direction. However, combined joints (rivet/bonded) will create a bearing area that induces another potential damage source aside from secondary bending moment on the edge of the stiffener. Another problem is that the structure is difficult to be inspected by using conventional methods because of limited accessibility. The use of embedded fiber Bragg grating (FBG) technology in the structure as a strain sensor can potentially solve the problem in structures that have a stiffness mismatch. The FBG can be used to detect and characterize delamination before it reaches a critical stage. The model used to represent this problem is a thin composite stiffened skin under two load cases: tension and three-point bending. Finite element modeling using a traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. Experiments were presented to determine the distribution of load in a combined joint under both loading cases using ideal loads to create a secondary bending moment and bearing loads in the stiffness-mismatched structure. In this research, the FBG successfully detected and characterized the delamination caused in both loading cases. In addition, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace the conventional mechanical graph in composite structural health monitoring in real applications.
