This paper presents an experimental and systematic investigation about how geometric parameters on a biplane configuration have an influence on aerodynamic parameters. This experimental investigation has been develope...This paper presents an experimental and systematic investigation about how geometric parameters on a biplane configuration have an influence on aerodynamic parameters. This experimental investigation has been developed in a two-dimensional approach. Theoretical studies about biplanes configurations have been developed in the past, but there is not enough information about experimental wind tunnel data at low Reynolds number. This two-dimensional study is a first step to further tridimensional investigations about the box wing configuration. The main objective of the study is to find the relationships between the geometrical parameters which present the best aerodynamic behavior： the highest lift, the lowest drag and the lowest slope of the pitching moment. A tridimensional wing-box model will be designed following the pattern of the two dimensional study conclusions. It will respond to the geometrical relationships that have been considered to show the better aerodynamic behavior. This box-wing model will be studied in the aim of comparing the advantages and disadvantages between this biplane configuration and the plane configuration, looking for implementing the box-wing in the UAV＇s field. Although the box wing configuration has been used in a small number of existing UAV, prestigious researchers have found it as a field of high aerodynamic and structural potential.展开更多
Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex(AJC)is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders,as well as...Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex(AJC)is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders,as well as an essential guide to the design of ankle–foot assistant devices.However,detailed analysis of the continuous 3D motion of the tibiotalar and subtalar joints during normal walking throughout the stance phase is still considered to be lacking.In this study,dynamic radiographs of the hindfoot were acquired from eight subjects during normal walking.Natural motions with six Degrees of Freedom(DOF)and the coupled patterns of the two joints were analyzed.It was found that the movements of the two joints were mostly in opposite directions(including rotation and translation),mainly in the early and late stages.There were significant differences in the Range of Motion(ROM)in Dorsiflexion/Plantarflexion(D/P),Inversion/Eversion(In/Ev),and Anterior–Posterior(AP)and Medial–Lateral(ML)translation of the tibiotalar and subtalar joints(p<0.05).Plantarflexion of the tibiotalar joint was coupled with eversion and posterior translation of the subtalar joint during the impact phase(R^(2)=0.87 and 0.86,respectively),and plantarflexion of the tibiotalar joint was coupled with inversion and anterior translation of the subtalar joint during the push-off phase(R^(2)=0.93 and 0.75,respectively).This coordinated coupled motion of the two joints may be a manifestation of the AJC to move flexibly while bearing weight and still have stability.展开更多
In this paper, the characteristics of the three-dimensional flow field around the circular cylinder members forming a square biplane grid were experimentally investigated by using a wind tunnel and a water tunnel. In ...In this paper, the characteristics of the three-dimensional flow field around the circular cylinder members forming a square biplane grid were experimentally investigated by using a wind tunnel and a water tunnel. In the wind tunnel testing, the span wise and circumference pressure distributions of surface on the circular cylinder were measured on the center mesh members formed by biplane grid in detail. Local drag coefficient was calculated from the surface pressure distributions. In addition, the flow visualization was performed in the water tunnel. As a result, it was suggested that the flow penetrating the contact region produced secondary-flow behind the biplane grid. Accordingly, the drag reduction would be caused by the presence of the secondary-flow.展开更多
The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the inter...The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the interphalangeal(IP)and metacarpophalangeal(MCP)joints during hand functional tasks remains challenging.To address this issue,advanced dynamic biplane radiography combined with a model-based 2D–3D tracking technique was employed to decode the inherent kinematics of the thumb IP and MCP joints during key pinch,tip pinch,palmar pinch and wide grasp.The results indicate that the functional tasks of the thumb are intricately modulated by the 3D rotational and translational motions of the IP and MCP joints.The IP joint exhibited the greatest flexion/extension range of motion during the tip pinch task(67.2°±8.4°),compared to smaller ranges in key pinch(27.6°±3.8°)and wide grasp(16.2°±7.1°)tasks.In the wide grasp task,the IP joint showed more movement in the radius/ulna direction(3.4±1.2 mm)compared to tip pinch(3.1±0.8 mm).Furthermore,the kinematic data of the IP joint challenge the traditional notion that the IP joint normally acts as a hinge mechanism.The results of this study help to elucidate the kinematics of human thumb IP and MCP joints and may provide new inspiration for the design of high-performance bionic hands or thumb prosthetics as well as for evaluating the outcomes of thumb therapeutic interventions and surgical procedures.展开更多
文摘This paper presents an experimental and systematic investigation about how geometric parameters on a biplane configuration have an influence on aerodynamic parameters. This experimental investigation has been developed in a two-dimensional approach. Theoretical studies about biplanes configurations have been developed in the past, but there is not enough information about experimental wind tunnel data at low Reynolds number. This two-dimensional study is a first step to further tridimensional investigations about the box wing configuration. The main objective of the study is to find the relationships between the geometrical parameters which present the best aerodynamic behavior： the highest lift, the lowest drag and the lowest slope of the pitching moment. A tridimensional wing-box model will be designed following the pattern of the two dimensional study conclusions. It will respond to the geometrical relationships that have been considered to show the better aerodynamic behavior. This box-wing model will be studied in the aim of comparing the advantages and disadvantages between this biplane configuration and the plane configuration, looking for implementing the box-wing in the UAV＇s field. Although the box wing configuration has been used in a small number of existing UAV, prestigious researchers have found it as a field of high aerodynamic and structural potential.
基金supported by the National Natural Science Foundation of China(52175270,91848204)the Project of Scientific and Technological Development Plan of Jilin Province(20220508130RC).
文摘Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex(AJC)is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders,as well as an essential guide to the design of ankle–foot assistant devices.However,detailed analysis of the continuous 3D motion of the tibiotalar and subtalar joints during normal walking throughout the stance phase is still considered to be lacking.In this study,dynamic radiographs of the hindfoot were acquired from eight subjects during normal walking.Natural motions with six Degrees of Freedom(DOF)and the coupled patterns of the two joints were analyzed.It was found that the movements of the two joints were mostly in opposite directions(including rotation and translation),mainly in the early and late stages.There were significant differences in the Range of Motion(ROM)in Dorsiflexion/Plantarflexion(D/P),Inversion/Eversion(In/Ev),and Anterior–Posterior(AP)and Medial–Lateral(ML)translation of the tibiotalar and subtalar joints(p<0.05).Plantarflexion of the tibiotalar joint was coupled with eversion and posterior translation of the subtalar joint during the impact phase(R^(2)=0.87 and 0.86,respectively),and plantarflexion of the tibiotalar joint was coupled with inversion and anterior translation of the subtalar joint during the push-off phase(R^(2)=0.93 and 0.75,respectively).This coordinated coupled motion of the two joints may be a manifestation of the AJC to move flexibly while bearing weight and still have stability.
文摘In this paper, the characteristics of the three-dimensional flow field around the circular cylinder members forming a square biplane grid were experimentally investigated by using a wind tunnel and a water tunnel. In the wind tunnel testing, the span wise and circumference pressure distributions of surface on the circular cylinder were measured on the center mesh members formed by biplane grid in detail. Local drag coefficient was calculated from the surface pressure distributions. In addition, the flow visualization was performed in the water tunnel. As a result, it was suggested that the flow penetrating the contact region produced secondary-flow behind the biplane grid. Accordingly, the drag reduction would be caused by the presence of the secondary-flow.
基金supported by the National Natural Science Foundation of China(No.52175270)the Project of Scientific and Technological Development Plan of Jilin Province(No.20220508130RC).
文摘The human thumb plays a crucial role in performing coordinated hand movements for precise tool use.However,quantifying and interpreting the kinematics and couplings of the six degrees of freedom(6DOF)between the interphalangeal(IP)and metacarpophalangeal(MCP)joints during hand functional tasks remains challenging.To address this issue,advanced dynamic biplane radiography combined with a model-based 2D–3D tracking technique was employed to decode the inherent kinematics of the thumb IP and MCP joints during key pinch,tip pinch,palmar pinch and wide grasp.The results indicate that the functional tasks of the thumb are intricately modulated by the 3D rotational and translational motions of the IP and MCP joints.The IP joint exhibited the greatest flexion/extension range of motion during the tip pinch task(67.2°±8.4°),compared to smaller ranges in key pinch(27.6°±3.8°)and wide grasp(16.2°±7.1°)tasks.In the wide grasp task,the IP joint showed more movement in the radius/ulna direction(3.4±1.2 mm)compared to tip pinch(3.1±0.8 mm).Furthermore,the kinematic data of the IP joint challenge the traditional notion that the IP joint normally acts as a hinge mechanism.The results of this study help to elucidate the kinematics of human thumb IP and MCP joints and may provide new inspiration for the design of high-performance bionic hands or thumb prosthetics as well as for evaluating the outcomes of thumb therapeutic interventions and surgical procedures.
