The Experts below are selected from a list of 214113 Experts worldwide ranked by ideXlab platform
Benio Kibushi - One of the best experts on this subject based on the ideXlab platform.
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local Dynamic Stability in temporal pattern of intersegmental coordination during various stride time and stride length combinations
Experimental Brain Research, 2019Co-Authors: Benio Kibushi, Toshio Moritani, Motoki KouzakiAbstract:For the regulation of walking speed, the central nervous system must select appropriate combinations of stride time and stride length (stride time–length combinations) and coordinate many joints or segments in the whole body. However, humans achieve both appropriate selection of stride time–length combinations and effortless coordination of joints or segments. Although this selection of stride time–length combination has been explained by minimized energy cost, it may also be explained by the Stability of kinematic coordination. Therefore, we investigated the Stability of kinematic coordination during walking across various stride time–length combinations. Whole body kinematic coordination was quantified as the kinematic synergies that represents the groups of simultaneously move segments (intersegmental coordination) and their activation patterns (temporal coordination). In addition, the maximum Lyapunov exponents were utilized to evaluate local Dynamic Stability. We calculated the maximum Lyapunov exponents in temporal coordination of kinematic synergies across various stride time–length combinations. The results showed that the maximum Lyapunov exponents of temporal coordination depended on stride time–length combinations. Moreover, the maximum Lyapunov exponents were high at fast walking speeds and very short stride length conditions. This result implies that fast walking speeds and very short stride length were associated with lower local Dynamic Stability of temporal coordination. We concluded that fast walking is associated with lower local Dynamic Stability of temporal coordination of kinematic synergies.
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Lower Local Dynamic Stability and Invariable Orbital Stability in the Activation of Muscle Synergies in Response to Accelerated Walking Speeds
'Frontiers Media SA', 2018Co-Authors: Benio Kibushi, Toshio Moritani, Shota Hagio, Motoki KouzakiAbstract:In order to achieve flexible and smooth walking, we must accomplish subtasks (e. g., loading response, forward propulsion or swing initiation) within a gait cycle. To evaluate subtasks within a gait cycle, the analysis of muscle synergies may be effective. In the case of walking, extracted sets of muscle synergies characterize muscle patterns that relate to the subtasks within a gait cycle. Although previous studies have reported that the muscle synergies of individuals with disorders reflect impairments, a way to investigate the inStability in the activations of muscle synergies themselves has not been proposed. Thus, we investigated the local Dynamic Stability and orbital Stability of activations of muscle synergies across various walking speeds using maximum Lyapunov exponents and maximum Floquet multipliers. We revealed that the local Dynamic Stability in the activations decreased with accelerated walking speeds. Contrary to the local Dynamic Stability, the orbital Stability of the activations was almost constant across walking speeds. In addition, the increasing rates of maximum Lyapunov exponents were different among the muscle synergies. Therefore, the local Dynamic Stability in the activations might depend on the requirement of motor output related to the subtasks within a gait cycle. We concluded that the local Dynamic Stability in the activation of muscle synergies decrease as walking speed accelerates. On the other hand, the orbital Stability is sustained across broad walking speeds
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Data_Sheet_1_Lower Local Dynamic Stability and Invariable Orbital Stability in the Activation of Muscle Synergies in Response to Accelerated Walking Speeds.docx
2018Co-Authors: Benio Kibushi, Toshio Moritani, Shota Hagio, Motoki KouzakiAbstract:In order to achieve flexible and smooth walking, we must accomplish subtasks (e. g., loading response, forward propulsion or swing initiation) within a gait cycle. To evaluate subtasks within a gait cycle, the analysis of muscle synergies may be effective. In the case of walking, extracted sets of muscle synergies characterize muscle patterns that relate to the subtasks within a gait cycle. Although previous studies have reported that the muscle synergies of individuals with disorders reflect impairments, a way to investigate the inStability in the activations of muscle synergies themselves has not been proposed. Thus, we investigated the local Dynamic Stability and orbital Stability of activations of muscle synergies across various walking speeds using maximum Lyapunov exponents and maximum Floquet multipliers. We revealed that the local Dynamic Stability in the activations decreased with accelerated walking speeds. Contrary to the local Dynamic Stability, the orbital Stability of the activations was almost constant across walking speeds. In addition, the increasing rates of maximum Lyapunov exponents were different among the muscle synergies. Therefore, the local Dynamic Stability in the activations might depend on the requirement of motor output related to the subtasks within a gait cycle. We concluded that the local Dynamic Stability in the activation of muscle synergies decrease as walking speed accelerates. On the other hand, the orbital Stability is sustained across broad walking speeds.
Motoki Kouzaki - One of the best experts on this subject based on the ideXlab platform.
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local Dynamic Stability in temporal pattern of intersegmental coordination during various stride time and stride length combinations
Experimental Brain Research, 2019Co-Authors: Benio Kibushi, Toshio Moritani, Motoki KouzakiAbstract:For the regulation of walking speed, the central nervous system must select appropriate combinations of stride time and stride length (stride time–length combinations) and coordinate many joints or segments in the whole body. However, humans achieve both appropriate selection of stride time–length combinations and effortless coordination of joints or segments. Although this selection of stride time–length combination has been explained by minimized energy cost, it may also be explained by the Stability of kinematic coordination. Therefore, we investigated the Stability of kinematic coordination during walking across various stride time–length combinations. Whole body kinematic coordination was quantified as the kinematic synergies that represents the groups of simultaneously move segments (intersegmental coordination) and their activation patterns (temporal coordination). In addition, the maximum Lyapunov exponents were utilized to evaluate local Dynamic Stability. We calculated the maximum Lyapunov exponents in temporal coordination of kinematic synergies across various stride time–length combinations. The results showed that the maximum Lyapunov exponents of temporal coordination depended on stride time–length combinations. Moreover, the maximum Lyapunov exponents were high at fast walking speeds and very short stride length conditions. This result implies that fast walking speeds and very short stride length were associated with lower local Dynamic Stability of temporal coordination. We concluded that fast walking is associated with lower local Dynamic Stability of temporal coordination of kinematic synergies.
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Lower Local Dynamic Stability and Invariable Orbital Stability in the Activation of Muscle Synergies in Response to Accelerated Walking Speeds
'Frontiers Media SA', 2018Co-Authors: Benio Kibushi, Toshio Moritani, Shota Hagio, Motoki KouzakiAbstract:In order to achieve flexible and smooth walking, we must accomplish subtasks (e. g., loading response, forward propulsion or swing initiation) within a gait cycle. To evaluate subtasks within a gait cycle, the analysis of muscle synergies may be effective. In the case of walking, extracted sets of muscle synergies characterize muscle patterns that relate to the subtasks within a gait cycle. Although previous studies have reported that the muscle synergies of individuals with disorders reflect impairments, a way to investigate the inStability in the activations of muscle synergies themselves has not been proposed. Thus, we investigated the local Dynamic Stability and orbital Stability of activations of muscle synergies across various walking speeds using maximum Lyapunov exponents and maximum Floquet multipliers. We revealed that the local Dynamic Stability in the activations decreased with accelerated walking speeds. Contrary to the local Dynamic Stability, the orbital Stability of the activations was almost constant across walking speeds. In addition, the increasing rates of maximum Lyapunov exponents were different among the muscle synergies. Therefore, the local Dynamic Stability in the activations might depend on the requirement of motor output related to the subtasks within a gait cycle. We concluded that the local Dynamic Stability in the activation of muscle synergies decrease as walking speed accelerates. On the other hand, the orbital Stability is sustained across broad walking speeds
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Data_Sheet_1_Lower Local Dynamic Stability and Invariable Orbital Stability in the Activation of Muscle Synergies in Response to Accelerated Walking Speeds.docx
2018Co-Authors: Benio Kibushi, Toshio Moritani, Shota Hagio, Motoki KouzakiAbstract:In order to achieve flexible and smooth walking, we must accomplish subtasks (e. g., loading response, forward propulsion or swing initiation) within a gait cycle. To evaluate subtasks within a gait cycle, the analysis of muscle synergies may be effective. In the case of walking, extracted sets of muscle synergies characterize muscle patterns that relate to the subtasks within a gait cycle. Although previous studies have reported that the muscle synergies of individuals with disorders reflect impairments, a way to investigate the inStability in the activations of muscle synergies themselves has not been proposed. Thus, we investigated the local Dynamic Stability and orbital Stability of activations of muscle synergies across various walking speeds using maximum Lyapunov exponents and maximum Floquet multipliers. We revealed that the local Dynamic Stability in the activations decreased with accelerated walking speeds. Contrary to the local Dynamic Stability, the orbital Stability of the activations was almost constant across walking speeds. In addition, the increasing rates of maximum Lyapunov exponents were different among the muscle synergies. Therefore, the local Dynamic Stability in the activations might depend on the requirement of motor output related to the subtasks within a gait cycle. We concluded that the local Dynamic Stability in the activation of muscle synergies decrease as walking speed accelerates. On the other hand, the orbital Stability is sustained across broad walking speeds.
Sritawat Kitipornchai - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stability of piezoelectric laminated cylindrical shells with delamination
Journal of Intelligent Material Systems and Structures, 2013Co-Authors: Jin Hua Yang, Jie Yang, Sritawat KitipornchaiAbstract:The Dynamic Stability of a composite laminated cylindrical shell containing a throughout delamination along circumferential direction integrated with piezoelectric layers at both inner and outer surfaces is investigated in this article. The Heaviside step function is used to describe the displacement components in the regions with and without delamination. Based on the classical shell theory, linear piezoelastic constitutive relationship, and variational principle, the governing equations of motion are derived and then solved by employing Rayleigh-Ritz method and Bolotin method to obtain the principal unstable region. Numerical results are presented in both tabular and graphical forms to show the effects of the piezoelectric layer; the length, depth, and location of the delamination; and the static axial force on the resonance frequency and the principal unstable region of the delaminated piezoelectric laminated shell.
Francesco Pellicano - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stability and sensitivity to geometric imperfections of strongly compressed circular cylindrical shells under Dynamic axial loads
Communications in Nonlinear Science and Numerical Simulation, 2009Co-Authors: Francesco PellicanoAbstract:Abstract In the present paper, the Dynamic Stability of circular cylindrical shells is investigated; the combined effect of compressive static and periodic axial loads is considered. The Sanders–Koiter theory is applied to model the nonlinear Dynamics of the system in the case of finite amplitude of vibration; Lagrange equations are used to reduce the nonlinear partial differential equations to a set of ordinary differential equations. The Dynamic Stability is investigated using direct numerical simulation and a dichotomic algorithm to find the inStability boundaries as the excitation frequency is varied; the effect of geometric imperfections is investigated in detail. The accuracy of the approach is checked by means of comparisons with the literature.
Chingcheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Stability of a sandwich beam with a constrained layer and electrorheological fluid core
Composite Structures, 2004Co-Authors: Jia-yi Yeh, Lien-wen Chen, Chingcheng WangAbstract:The Dynamic Stability problem of a sandwich beam with a constrained layer and an electrorheological fluid core subjected to an axial Dynamic force are studied. Rheological properties of an electrorheological material, such as viscosity, plasticity, and elasticity may be changed by applying an electric field. Effects of the natural frequencies, static buckling loads and loss factors on the Dynamic Stability behavior of the sandwich beam are investigated. The finite element method and the harmonic balance method are used to calculate the inStability regions of the sandwich beam. The electrorheological core is found to have a significant effect on the Dynamic Stability regions.
